This series expands the XDP TX metadata framework to allow user applications to pass per packet 64-bit launch time directly to the kernel driver, requesting launch time hardware offload support. The XDP TX metadata framework will not perform any clock conversion or packet reordering.
Please note that the role of Tx metadata is just to pass the launch time, not to enable the offload feature. Users will need to enable the launch time hardware offload feature of the device by using the respective command, such as the tc-etf command.
Although some devices use the tc-etf command to enable their launch time hardware offload feature, xsk packets will not go through the etf qdisc. Therefore, in my opinion, the launch time should always be based on the PTP Hardware Clock (PHC). Thus, i did not include a clock ID to indicate the clock source.
To simplify the test steps, I modified the xdp_hw_metadata bpf self-test tool in such a way that it will set the launch time based on the offset provided by the user and the value of the Receive Hardware Timestamp, which is against the PHC. This will eliminate the need to discipline System Clock with the PHC and then use clock_gettime() to get the time.
Please note that AF_XDP lacks a feedback mechanism to inform the application if the requested launch time is invalid. So, users are expected to familiar with the horizon of the launch time of the device they use and not request a launch time that is beyond the horizon. Otherwise, the driver might interpret the launch time incorrectly and react wrongly. For stmmac and igc, where modulo computation is used, a launch time larger than the horizon will cause the device to transmit the packet earlier that the requested launch time.
Although there is no feedback mechanism for the launch time request for now, user still can check whether the requested launch time is working or not, by requesting the Transmit Completion Hardware Timestamp.
V8: - check the number of used descriptor in xsk_tx_metadata_request() by using used_desc of struct igc_metadata_request, and then decreases the budget with it (Maciej)
V7: https://lore.kernel.org/netdev/20250204004907.789330-1-yoong.siang.song@inte... - split the refactoring code of igc empty packet insertion into a separate commit (Faizal) - add explanation on why the value "4" is used as igc transmit budget (Faizal) - perform a stress test by sending 1000 packets with 10ms interval and launch time set to 500us in the future (Faizal & Yong Liang)
V6: https://lore.kernel.org/netdev/20250116155350.555374-1-yoong.siang.song@inte... - fix selftest build errors by using asprintf() and realloc(), instead of managing the buffer sizes manually (Daniel, Stanislav)
V5: https://lore.kernel.org/netdev/20250114152718.120588-1-yoong.siang.song@inte... - change netdev feature name from tx-launch-time to tx-launch-time-fifo to explicitly state the FIFO behaviour (Stanislav) - improve the looping of xdp_hw_metadata app to wait for packet tx completion to be more readable by using clock_gettime() (Stanislav) - add launch time setup steps into xdp_hw_metadata app (Stanislav)
V4: https://lore.kernel.org/netdev/20250106135506.9687-1-yoong.siang.song@intel.... - added XDP launch time support to the igc driver (Jesper & Florian) - added per-driver launch time limitation on xsk-tx-metadata.rst (Jesper) - added explanation on FIFO behavior on xsk-tx-metadata.rst (Jakub) - added step to enable launch time in the commit message (Jesper & Willem) - explicitly documented the type of launch_time and which clock source it is against (Willem)
V3: https://lore.kernel.org/netdev/20231203165129.1740512-1-yoong.siang.song@int... - renamed to use launch time (Jesper & Willem) - changed the default launch time in xdp_hw_metadata apps from 1s to 0.1s because some NICs do not support such a large future time.
V2: https://lore.kernel.org/netdev/20231201062421.1074768-1-yoong.siang.song@int... - renamed to use Earliest TxTime First (Willem) - renamed to use txtime (Willem)
V1: https://lore.kernel.org/netdev/20231130162028.852006-1-yoong.siang.song@inte...
Song Yoong Siang (5): xsk: Add launch time hardware offload support to XDP Tx metadata selftests/bpf: Add launch time request to xdp_hw_metadata net: stmmac: Add launch time support to XDP ZC igc: Refactor empty packet insertion into a reusable function igc: Add launch time support to XDP ZC
Documentation/netlink/specs/netdev.yaml | 4 + Documentation/networking/xsk-tx-metadata.rst | 62 +++++++ drivers/net/ethernet/intel/igc/igc.h | 1 + drivers/net/ethernet/intel/igc/igc_main.c | 94 +++++++--- drivers/net/ethernet/stmicro/stmmac/stmmac.h | 2 + .../net/ethernet/stmicro/stmmac/stmmac_main.c | 13 ++ include/net/xdp_sock.h | 10 ++ include/net/xdp_sock_drv.h | 1 + include/uapi/linux/if_xdp.h | 10 ++ include/uapi/linux/netdev.h | 3 + net/core/netdev-genl.c | 2 + net/xdp/xsk.c | 3 + tools/include/uapi/linux/if_xdp.h | 10 ++ tools/include/uapi/linux/netdev.h | 3 + tools/testing/selftests/bpf/xdp_hw_metadata.c | 168 +++++++++++++++++- 15 files changed, 359 insertions(+), 27 deletions(-)
Extend the XDP Tx metadata framework so that user can requests launch time hardware offload, where the Ethernet device will schedule the packet for transmission at a pre-determined time called launch time. The value of launch time is communicated from user space to Ethernet driver via launch_time field of struct xsk_tx_metadata.
Suggested-by: Stanislav Fomichev sdf@fomichev.me Signed-off-by: Song Yoong Siang yoong.siang.song@intel.com Acked-by: Stanislav Fomichev sdf@fomichev.me --- Documentation/netlink/specs/netdev.yaml | 4 ++ Documentation/networking/xsk-tx-metadata.rst | 62 ++++++++++++++++++++ include/net/xdp_sock.h | 10 ++++ include/net/xdp_sock_drv.h | 1 + include/uapi/linux/if_xdp.h | 10 ++++ include/uapi/linux/netdev.h | 3 + net/core/netdev-genl.c | 2 + net/xdp/xsk.c | 3 + tools/include/uapi/linux/if_xdp.h | 10 ++++ tools/include/uapi/linux/netdev.h | 3 + 10 files changed, 108 insertions(+)
diff --git a/Documentation/netlink/specs/netdev.yaml b/Documentation/netlink/specs/netdev.yaml index cbb544bd6c84..901b5afb3df0 100644 --- a/Documentation/netlink/specs/netdev.yaml +++ b/Documentation/netlink/specs/netdev.yaml @@ -70,6 +70,10 @@ definitions: name: tx-checksum doc: L3 checksum HW offload is supported by the driver. + - + name: tx-launch-time-fifo + doc: + Launch time HW offload is supported by the driver. - name: queue-type type: enum diff --git a/Documentation/networking/xsk-tx-metadata.rst b/Documentation/networking/xsk-tx-metadata.rst index e76b0cfc32f7..df53a10ccac3 100644 --- a/Documentation/networking/xsk-tx-metadata.rst +++ b/Documentation/networking/xsk-tx-metadata.rst @@ -50,6 +50,10 @@ The flags field enables the particular offload: checksum. ``csum_start`` specifies byte offset of where the checksumming should start and ``csum_offset`` specifies byte offset where the device should store the computed checksum. +- ``XDP_TXMD_FLAGS_LAUNCH_TIME``: requests the device to schedule the + packet for transmission at a pre-determined time called launch time. The + value of launch time is indicated by ``launch_time`` field of + ``union xsk_tx_metadata``.
Besides the flags above, in order to trigger the offloads, the first packet's ``struct xdp_desc`` descriptor should set ``XDP_TX_METADATA`` @@ -65,6 +69,63 @@ In this case, when running in ``XDK_COPY`` mode, the TX checksum is calculated on the CPU. Do not enable this option in production because it will negatively affect performance.
+Launch Time +=========== + +The value of the requested launch time should be based on the device's PTP +Hardware Clock (PHC) to ensure accuracy. AF_XDP takes a different data path +compared to the ETF queuing discipline, which organizes packets and delays +their transmission. Instead, AF_XDP immediately hands off the packets to +the device driver without rearranging their order or holding them prior to +transmission. Since the driver maintains FIFO behavior and does not perform +packet reordering, a packet with a launch time request will block other +packets in the same Tx Queue until it is sent. Therefore, it is recommended +to allocate separate queue for scheduling traffic that is intended for +future transmission. + +In scenarios where the launch time offload feature is disabled, the device +driver is expected to disregard the launch time request. For correct +interpretation and meaningful operation, the launch time should never be +set to a value larger than the farthest programmable time in the future +(the horizon). Different devices have different hardware limitations on the +launch time offload feature. + +stmmac driver +------------- + +For stmmac, TSO and launch time (TBS) features are mutually exclusive for +each individual Tx Queue. By default, the driver configures Tx Queue 0 to +support TSO and the rest of the Tx Queues to support TBS. The launch time +hardware offload feature can be enabled or disabled by using the tc-etf +command to call the driver's ndo_setup_tc() callback. + +The value of the launch time that is programmed in the Enhanced Normal +Transmit Descriptors is a 32-bit value, where the most significant 8 bits +represent the time in seconds and the remaining 24 bits represent the time +in 256 ns increments. The programmed launch time is compared against the +PTP time (bits[39:8]) and rolls over after 256 seconds. Therefore, the +horizon of the launch time for dwmac4 and dwxlgmac2 is 128 seconds in the +future. + +igc driver +---------- + +For igc, all four Tx Queues support the launch time feature. The launch +time hardware offload feature can be enabled or disabled by using the +tc-etf command to call the driver's ndo_setup_tc() callback. When entering +TSN mode, the igc driver will reset the device and create a default Qbv +schedule with a 1-second cycle time, with all Tx Queues open at all times. + +The value of the launch time that is programmed in the Advanced Transmit +Context Descriptor is a relative offset to the starting time of the Qbv +transmission window of the queue. The Frst flag of the descriptor can be +set to schedule the packet for the next Qbv cycle. Therefore, the horizon +of the launch time for i225 and i226 is the ending time of the next cycle +of the Qbv transmission window of the queue. For example, when the Qbv +cycle time is set to 1 second, the horizon of the launch time ranges +from 1 second to 2 seconds, depending on where the Qbv cycle is currently +running. + Querying Device Capabilities ============================
@@ -74,6 +135,7 @@ Refer to ``xsk-flags`` features bitmask in
- ``tx-timestamp``: device supports ``XDP_TXMD_FLAGS_TIMESTAMP`` - ``tx-checksum``: device supports ``XDP_TXMD_FLAGS_CHECKSUM`` +- ``tx-launch-time-fifo``: device supports ``XDP_TXMD_FLAGS_LAUNCH_TIME``
See ``tools/net/ynl/samples/netdev.c`` on how to query this information.
diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h index bfe625b55d55..a58ae7589d12 100644 --- a/include/net/xdp_sock.h +++ b/include/net/xdp_sock.h @@ -110,11 +110,16 @@ struct xdp_sock { * indicates position where checksumming should start. * csum_offset indicates position where checksum should be stored. * + * void (*tmo_request_launch_time)(u64 launch_time, void *priv) + * Called when AF_XDP frame requested launch time HW offload support. + * launch_time indicates the PTP time at which the device can schedule the + * packet for transmission. */ struct xsk_tx_metadata_ops { void (*tmo_request_timestamp)(void *priv); u64 (*tmo_fill_timestamp)(void *priv); void (*tmo_request_checksum)(u16 csum_start, u16 csum_offset, void *priv); + void (*tmo_request_launch_time)(u64 launch_time, void *priv); };
#ifdef CONFIG_XDP_SOCKETS @@ -162,6 +167,11 @@ static inline void xsk_tx_metadata_request(const struct xsk_tx_metadata *meta, if (!meta) return;
+ if (ops->tmo_request_launch_time) + if (meta->flags & XDP_TXMD_FLAGS_LAUNCH_TIME) + ops->tmo_request_launch_time(meta->request.launch_time, + priv); + if (ops->tmo_request_timestamp) if (meta->flags & XDP_TXMD_FLAGS_TIMESTAMP) ops->tmo_request_timestamp(priv); diff --git a/include/net/xdp_sock_drv.h b/include/net/xdp_sock_drv.h index 784cd34f5bba..fe4afb251719 100644 --- a/include/net/xdp_sock_drv.h +++ b/include/net/xdp_sock_drv.h @@ -199,6 +199,7 @@ static inline void *xsk_buff_raw_get_data(struct xsk_buff_pool *pool, u64 addr) #define XDP_TXMD_FLAGS_VALID ( \ XDP_TXMD_FLAGS_TIMESTAMP | \ XDP_TXMD_FLAGS_CHECKSUM | \ + XDP_TXMD_FLAGS_LAUNCH_TIME | \ 0)
static inline bool diff --git a/include/uapi/linux/if_xdp.h b/include/uapi/linux/if_xdp.h index 42ec5ddaab8d..42869770776e 100644 --- a/include/uapi/linux/if_xdp.h +++ b/include/uapi/linux/if_xdp.h @@ -127,6 +127,12 @@ struct xdp_options { */ #define XDP_TXMD_FLAGS_CHECKSUM (1 << 1)
+/* Request launch time hardware offload. The device will schedule the packet for + * transmission at a pre-determined time called launch time. The value of + * launch time is communicated via launch_time field of struct xsk_tx_metadata. + */ +#define XDP_TXMD_FLAGS_LAUNCH_TIME (1 << 2) + /* AF_XDP offloads request. 'request' union member is consumed by the driver * when the packet is being transmitted. 'completion' union member is * filled by the driver when the transmit completion arrives. @@ -142,6 +148,10 @@ struct xsk_tx_metadata { __u16 csum_start; /* Offset from csum_start where checksum should be stored. */ __u16 csum_offset; + + /* XDP_TXMD_FLAGS_LAUNCH_TIME */ + /* Launch time in nanosecond against the PTP HW Clock */ + __u64 launch_time; } request;
struct { diff --git a/include/uapi/linux/netdev.h b/include/uapi/linux/netdev.h index e4be227d3ad6..5ab85f4af009 100644 --- a/include/uapi/linux/netdev.h +++ b/include/uapi/linux/netdev.h @@ -59,10 +59,13 @@ enum netdev_xdp_rx_metadata { * by the driver. * @NETDEV_XSK_FLAGS_TX_CHECKSUM: L3 checksum HW offload is supported by the * driver. + * @NETDEV_XSK_FLAGS_LAUNCH_TIME: Launch Time HW offload is supported by the + * driver. */ enum netdev_xsk_flags { NETDEV_XSK_FLAGS_TX_TIMESTAMP = 1, NETDEV_XSK_FLAGS_TX_CHECKSUM = 2, + NETDEV_XSK_FLAGS_LAUNCH_TIME = 4, };
enum netdev_queue_type { diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c index 715f85c6b62e..9b1e8b846d79 100644 --- a/net/core/netdev-genl.c +++ b/net/core/netdev-genl.c @@ -52,6 +52,8 @@ XDP_METADATA_KFUNC_xxx xsk_features |= NETDEV_XSK_FLAGS_TX_TIMESTAMP; if (netdev->xsk_tx_metadata_ops->tmo_request_checksum) xsk_features |= NETDEV_XSK_FLAGS_TX_CHECKSUM; + if (netdev->xsk_tx_metadata_ops->tmo_request_launch_time) + xsk_features |= NETDEV_XSK_FLAGS_LAUNCH_TIME; }
if (nla_put_u32(rsp, NETDEV_A_DEV_IFINDEX, netdev->ifindex) || diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index 89d2bef96469..41093ea63700 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -742,6 +742,9 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, goto free_err; } } + + if (meta->flags & XDP_TXMD_FLAGS_LAUNCH_TIME) + skb->skb_mstamp_ns = meta->request.launch_time; } }
diff --git a/tools/include/uapi/linux/if_xdp.h b/tools/include/uapi/linux/if_xdp.h index 42ec5ddaab8d..42869770776e 100644 --- a/tools/include/uapi/linux/if_xdp.h +++ b/tools/include/uapi/linux/if_xdp.h @@ -127,6 +127,12 @@ struct xdp_options { */ #define XDP_TXMD_FLAGS_CHECKSUM (1 << 1)
+/* Request launch time hardware offload. The device will schedule the packet for + * transmission at a pre-determined time called launch time. The value of + * launch time is communicated via launch_time field of struct xsk_tx_metadata. + */ +#define XDP_TXMD_FLAGS_LAUNCH_TIME (1 << 2) + /* AF_XDP offloads request. 'request' union member is consumed by the driver * when the packet is being transmitted. 'completion' union member is * filled by the driver when the transmit completion arrives. @@ -142,6 +148,10 @@ struct xsk_tx_metadata { __u16 csum_start; /* Offset from csum_start where checksum should be stored. */ __u16 csum_offset; + + /* XDP_TXMD_FLAGS_LAUNCH_TIME */ + /* Launch time in nanosecond against the PTP HW Clock */ + __u64 launch_time; } request;
struct { diff --git a/tools/include/uapi/linux/netdev.h b/tools/include/uapi/linux/netdev.h index e4be227d3ad6..5ab85f4af009 100644 --- a/tools/include/uapi/linux/netdev.h +++ b/tools/include/uapi/linux/netdev.h @@ -59,10 +59,13 @@ enum netdev_xdp_rx_metadata { * by the driver. * @NETDEV_XSK_FLAGS_TX_CHECKSUM: L3 checksum HW offload is supported by the * driver. + * @NETDEV_XSK_FLAGS_LAUNCH_TIME: Launch Time HW offload is supported by the + * driver. */ enum netdev_xsk_flags { NETDEV_XSK_FLAGS_TX_TIMESTAMP = 1, NETDEV_XSK_FLAGS_TX_CHECKSUM = 2, + NETDEV_XSK_FLAGS_LAUNCH_TIME = 4, };
enum netdev_queue_type {
Add launch time hardware offload request to xdp_hw_metadata. Users can configure the delta of launch time relative to HW RX-time using the "-l" argument. By default, the delta is set to 0 ns, which means the launch time is disabled. By setting the delta to a non-zero value, the launch time hardware offload feature will be enabled and requested. Additionally, users can configure the Tx Queue to be enabled with the launch time hardware offload using the "-L" argument. By default, Tx Queue 0 will be used.
Signed-off-by: Song Yoong Siang yoong.siang.song@intel.com Acked-by: Stanislav Fomichev sdf@fomichev.me --- tools/testing/selftests/bpf/xdp_hw_metadata.c | 168 +++++++++++++++++- 1 file changed, 163 insertions(+), 5 deletions(-)
diff --git a/tools/testing/selftests/bpf/xdp_hw_metadata.c b/tools/testing/selftests/bpf/xdp_hw_metadata.c index 6f7b15d6c6ed..3d8de0d4c96a 100644 --- a/tools/testing/selftests/bpf/xdp_hw_metadata.c +++ b/tools/testing/selftests/bpf/xdp_hw_metadata.c @@ -13,6 +13,7 @@ * - UDP 9091 packets trigger TX reply * - TX HW timestamp is requested and reported back upon completion * - TX checksum is requested + * - TX launch time HW offload is requested for transmission */
#include <test_progs.h> @@ -37,6 +38,15 @@ #include <time.h> #include <unistd.h> #include <libgen.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/ioctl.h> +#include <linux/pkt_sched.h> +#include <linux/pkt_cls.h> +#include <linux/ethtool.h> +#include <sys/socket.h> +#include <arpa/inet.h>
#include "xdp_metadata.h"
@@ -64,6 +74,18 @@ int rxq; bool skip_tx; __u64 last_hw_rx_timestamp; __u64 last_xdp_rx_timestamp; +__u64 last_launch_time; +__u64 launch_time_delta_to_hw_rx_timestamp; +int launch_time_queue; + +#define run_command(cmd, ...) \ +({ \ + char command[1024]; \ + memset(command, 0, sizeof(command)); \ + snprintf(command, sizeof(command), cmd, ##__VA_ARGS__); \ + fprintf(stderr, "Running: %s\n", command); \ + system(command); \ +})
void test__fail(void) { /* for network_helpers.c */ }
@@ -298,6 +320,12 @@ static bool complete_tx(struct xsk *xsk, clockid_t clock_id) if (meta->completion.tx_timestamp) { __u64 ref_tstamp = gettime(clock_id);
+ if (launch_time_delta_to_hw_rx_timestamp) { + print_tstamp_delta("HW Launch-time", + "HW TX-complete-time", + last_launch_time, + meta->completion.tx_timestamp); + } print_tstamp_delta("HW TX-complete-time", "User TX-complete-time", meta->completion.tx_timestamp, ref_tstamp); print_tstamp_delta("XDP RX-time", "User TX-complete-time", @@ -395,6 +423,17 @@ static void ping_pong(struct xsk *xsk, void *rx_packet, clockid_t clock_id) xsk, ntohs(udph->check), ntohs(want_csum), meta->request.csum_start, meta->request.csum_offset);
+ /* Set the value of launch time */ + if (launch_time_delta_to_hw_rx_timestamp) { + meta->flags |= XDP_TXMD_FLAGS_LAUNCH_TIME; + meta->request.launch_time = last_hw_rx_timestamp + + launch_time_delta_to_hw_rx_timestamp; + last_launch_time = meta->request.launch_time; + print_tstamp_delta("HW RX-time", "HW Launch-time", + last_hw_rx_timestamp, + meta->request.launch_time); + } + memcpy(data, rx_packet, len); /* don't share umem chunk for simplicity */ tx_desc->options |= XDP_TX_METADATA; tx_desc->len = len; @@ -407,6 +446,7 @@ static int verify_metadata(struct xsk *rx_xsk, int rxq, int server_fd, clockid_t const struct xdp_desc *rx_desc; struct pollfd fds[rxq + 1]; __u64 comp_addr; + __u64 deadline; __u64 addr; __u32 idx = 0; int ret; @@ -477,9 +517,15 @@ static int verify_metadata(struct xsk *rx_xsk, int rxq, int server_fd, clockid_t if (ret) printf("kick_tx ret=%d\n", ret);
- for (int j = 0; j < 500; j++) { + /* wait 1 second + cover launch time */ + deadline = gettime(clock_id) + + NANOSEC_PER_SEC + + launch_time_delta_to_hw_rx_timestamp; + while (true) { if (complete_tx(xsk, clock_id)) break; + if (gettime(clock_id) >= deadline) + break; usleep(10); } } @@ -608,6 +654,10 @@ static void print_usage(void) " -h Display this help and exit\n\n" " -m Enable multi-buffer XDP for larger MTU\n" " -r Don't generate AF_XDP reply (rx metadata only)\n" + " -l Delta of launch time relative to HW RX-time in ns\n" + " default: 0 ns (launch time request is disabled)\n" + " -L Tx Queue to be enabled with launch time offload\n" + " default: 0 (Tx Queue 0)\n" "Generate test packets on the other machine with:\n" " echo -n xdp | nc -u -q1 <dst_ip> 9091\n";
@@ -618,7 +668,7 @@ static void read_args(int argc, char *argv[]) { int opt;
- while ((opt = getopt(argc, argv, "chmr")) != -1) { + while ((opt = getopt(argc, argv, "chmrl:L:")) != -1) { switch (opt) { case 'c': bind_flags &= ~XDP_USE_NEED_WAKEUP; @@ -634,6 +684,12 @@ static void read_args(int argc, char *argv[]) case 'r': skip_tx = true; break; + case 'l': + launch_time_delta_to_hw_rx_timestamp = atoll(optarg); + break; + case 'L': + launch_time_queue = atoll(optarg); + break; case '?': if (isprint(optopt)) fprintf(stderr, "Unknown option: -%c\n", optopt); @@ -657,23 +713,118 @@ static void read_args(int argc, char *argv[]) error(-1, errno, "Invalid interface name"); }
+void clean_existing_configurations(void) +{ + /* Check and delete root qdisc if exists */ + if (run_command("sudo tc qdisc show dev %s | grep -q 'qdisc mqprio 8001:'", ifname) == 0) + run_command("sudo tc qdisc del dev %s root", ifname); + + /* Check and delete ingress qdisc if exists */ + if (run_command("sudo tc qdisc show dev %s | grep -q 'qdisc ingress ffff:'", ifname) == 0) + run_command("sudo tc qdisc del dev %s ingress", ifname); + + /* Check and delete ethtool filters if any exist */ + if (run_command("sudo ethtool -n %s | grep -q 'Filter:'", ifname) == 0) { + run_command("sudo ethtool -n %s | grep 'Filter:' | awk '{print $2}' | xargs -n1 sudo ethtool -N %s delete >&2", + ifname, ifname); + } +} + +#define MAX_TC 16 + int main(int argc, char *argv[]) { clockid_t clock_id = CLOCK_TAI; + struct bpf_program *prog; int server_fd = -1; + size_t map_len = 0; + size_t que_len = 0; + char *buf = NULL; + char *map = NULL; + char *que = NULL; + char *tmp = NULL; + int tc = 0; int ret; int i;
- struct bpf_program *prog; - read_args(argc, argv);
rxq = rxq_num(ifname); - printf("rxq: %d\n", rxq);
+ if (launch_time_queue >= rxq || launch_time_queue < 0) + error(1, 0, "Invalid launch_time_queue."); + + clean_existing_configurations(); + sleep(1); + + /* Enable tx and rx hardware timestamping */ hwtstamp_enable(ifname);
+ /* Prepare priority to traffic class map for tc-mqprio */ + for (i = 0; i < MAX_TC; i++) { + if (i < rxq) + tc = i; + + if (asprintf(&buf, "%d ", tc) == -1) { + printf("Failed to malloc buf for tc map.\n"); + goto free_mem; + } + + map_len += strlen(buf); + tmp = realloc(map, map_len + 1); + if (!tmp) { + printf("Failed to realloc tc map.\n"); + goto free_mem; + } + map = tmp; + strcat(map, buf); + free(buf); + buf = NULL; + } + + /* Prepare traffic class to hardware queue map for tc-mqprio */ + for (i = 0; i <= tc; i++) { + if (asprintf(&buf, "1@%d ", i) == -1) { + printf("Failed to malloc buf for tc queues.\n"); + goto free_mem; + } + + que_len += strlen(buf); + tmp = realloc(que, que_len + 1); + if (!tmp) { + printf("Failed to realloc tc queues.\n"); + goto free_mem; + } + que = tmp; + strcat(que, buf); + free(buf); + buf = NULL; + } + + /* Add mqprio qdisc */ + run_command("sudo tc qdisc add dev %s handle 8001: parent root mqprio num_tc %d map %squeues %shw 0", + ifname, tc + 1, map, que); + + /* To test launch time, send UDP packet with VLAN priority 1 to port 9091 */ + if (launch_time_delta_to_hw_rx_timestamp) { + /* Enable launch time hardware offload on launch_time_queue */ + run_command("sudo tc qdisc replace dev %s parent 8001:%d etf offload clockid CLOCK_TAI delta 500000", + ifname, launch_time_queue + 1); + sleep(1); + + /* Route incoming packet with VLAN priority 1 into launch_time_queue */ + if (run_command("sudo ethtool -N %s flow-type ether vlan 0x2000 vlan-mask 0x1FFF action %d", + ifname, launch_time_queue)) { + run_command("sudo tc qdisc add dev %s ingress", ifname); + run_command("sudo tc filter add dev %s parent ffff: protocol 802.1Q flower vlan_prio 1 hw_tc %d", + ifname, launch_time_queue); + } + + /* Enable VLAN tag stripping offload */ + run_command("sudo ethtool -K %s rxvlan on", ifname); + } + rx_xsk = malloc(sizeof(struct xsk) * rxq); if (!rx_xsk) error(1, ENOMEM, "malloc"); @@ -733,4 +884,11 @@ int main(int argc, char *argv[]) cleanup(); if (ret) error(1, -ret, "verify_metadata"); + + clean_existing_configurations(); + +free_mem: + free(buf); + free(map); + free(que); }
Enable launch time (Time-Based Scheduling) support for XDP zero copy via the XDP Tx metadata framework.
This patch has been tested with tools/testing/selftests/bpf/xdp_hw_metadata on Intel Tiger Lake platform. Below are the test steps and result.
Test 1: Send a single packet with the launch time set to 1 s in the future.
Test steps: 1. On the DUT, start the xdp_hw_metadata selftest application: $ sudo ./xdp_hw_metadata enp0s30f4 -l 1000000000 -L 1
2. On the Link Partner, send a UDP packet with VLAN priority 1 to port 9091 of the DUT.
Result: When the launch time is set to 1 s in the future, the delta between the launch time and the transmit hardware timestamp is 16.963 us, as shown in printout of the xdp_hw_metadata application below. 0x55b5864717a8: rx_desc[4]->addr=88100 addr=88100 comp_addr=88100 EoP No rx_hash, err=-95 HW RX-time: 1734579065767717328 (sec:1734579065.7677) delta to User RX-time sec:0.0004 (375.624 usec) XDP RX-time: 1734579065768004454 (sec:1734579065.7680) delta to User RX-time sec:0.0001 (88.498 usec) No rx_vlan_tci or rx_vlan_proto, err=-95 0x55b5864717a8: ping-pong with csum=5619 (want 0000) csum_start=34 csum_offset=6 HW RX-time: 1734579065767717328 (sec:1734579065.7677) delta to HW Launch-time sec:1.0000 (1000000.000 usec) 0x55b5864717a8: complete tx idx=4 addr=4018 HW Launch-time: 1734579066767717328 (sec:1734579066.7677) delta to HW TX-complete-time sec:0.0000 (16.963 usec) HW TX-complete-time: 1734579066767734291 (sec:1734579066.7677) delta to User TX-complete-time sec:0.0001 (130.408 usec) XDP RX-time: 1734579065768004454 (sec:1734579065.7680) delta to User TX-complete-time sec:0.9999 (999860.245 usec) HW RX-time: 1734579065767717328 (sec:1734579065.7677) delta to HW TX-complete-time sec:1.0000 (1000016.963 usec) 0x55b5864717a8: complete rx idx=132 addr=88100
Test 2: Send 1000 packets with a 10 ms interval and the launch time set to 500 us in the future.
Test steps: 1. On the DUT, start the xdp_hw_metadata selftest application: $ sudo chrt -f 99 ./xdp_hw_metadata enp0s30f4 -l 500000 -L 1 > \ /dev/shm/result.log
2. On the Link Partner, send 1000 UDP packets with a 10 ms interval and VLAN priority 1 to port 9091 of the DUT.
Result: When the launch time is set to 500 us in the future, the average delta between the launch time and the transmit hardware timestamp is 13.854 us, as shown in the analysis of /dev/shm/result.log below. The XDP launch time works correctly in sending 1000 packets continuously. Min delta: 08.410 us Avr delta: 13.854 us Max delta: 17.076 us Total packets forwarded: 1000
Signed-off-by: Song Yoong Siang yoong.siang.song@intel.com Reviewed-by: Choong Yong Liang yong.liang.choong@linux.intel.com --- drivers/net/ethernet/stmicro/stmmac/stmmac.h | 2 ++ drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 13 +++++++++++++ 2 files changed, 15 insertions(+)
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h index f05cae103d83..925d8b97a42b 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h @@ -106,6 +106,8 @@ struct stmmac_metadata_request { struct stmmac_priv *priv; struct dma_desc *tx_desc; bool *set_ic; + struct dma_edesc *edesc; + int tbs; };
struct stmmac_xsk_tx_complete { diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index d04543e5697b..5e5d24924ce7 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c @@ -2514,9 +2514,20 @@ static u64 stmmac_xsk_fill_timestamp(void *_priv) return 0; }
+static void stmmac_xsk_request_launch_time(u64 launch_time, void *_priv) +{ + struct stmmac_metadata_request *meta_req = _priv; + struct timespec64 ts = ns_to_timespec64(launch_time); + + if (meta_req->tbs & STMMAC_TBS_EN) + stmmac_set_desc_tbs(meta_req->priv, meta_req->edesc, ts.tv_sec, + ts.tv_nsec); +} + static const struct xsk_tx_metadata_ops stmmac_xsk_tx_metadata_ops = { .tmo_request_timestamp = stmmac_xsk_request_timestamp, .tmo_fill_timestamp = stmmac_xsk_fill_timestamp, + .tmo_request_launch_time = stmmac_xsk_request_launch_time, };
static bool stmmac_xdp_xmit_zc(struct stmmac_priv *priv, u32 queue, u32 budget) @@ -2600,6 +2611,8 @@ static bool stmmac_xdp_xmit_zc(struct stmmac_priv *priv, u32 queue, u32 budget) meta_req.priv = priv; meta_req.tx_desc = tx_desc; meta_req.set_ic = &set_ic; + meta_req.tbs = tx_q->tbs; + meta_req.edesc = &tx_q->dma_entx[entry]; xsk_tx_metadata_request(meta, &stmmac_xsk_tx_metadata_ops, &meta_req); if (set_ic) {
Refactor the code for inserting an empty packet into a new function igc_insert_empty_packet(). This change extracts the logic for inserting an empty packet from igc_xmit_frame_ring() into a separate function, allowing it to be reused in future implementations, such as the XDP zero copy transmit function.
This patch introduces no functional changes.
Signed-off-by: Song Yoong Siang yoong.siang.song@intel.com Reviewed-by: Faizal Rahim faizal.abdul.rahim@linux.intel.com --- drivers/net/ethernet/intel/igc/igc_main.c | 42 ++++++++++++----------- 1 file changed, 22 insertions(+), 20 deletions(-)
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c index 21f318f12a8d..553d6d82af0d 100644 --- a/drivers/net/ethernet/intel/igc/igc_main.c +++ b/drivers/net/ethernet/intel/igc/igc_main.c @@ -1566,6 +1566,26 @@ static bool igc_request_tx_tstamp(struct igc_adapter *adapter, struct sk_buff *s return false; }
+static void igc_insert_empty_packet(struct igc_ring *tx_ring) +{ + struct igc_tx_buffer *empty_info; + struct sk_buff *empty; + void *data; + + empty_info = &tx_ring->tx_buffer_info[tx_ring->next_to_use]; + empty = alloc_skb(IGC_EMPTY_FRAME_SIZE, GFP_ATOMIC); + if (!empty) + return; + + data = skb_put(empty, IGC_EMPTY_FRAME_SIZE); + memset(data, 0, IGC_EMPTY_FRAME_SIZE); + + igc_tx_ctxtdesc(tx_ring, 0, false, 0, 0, 0); + + if (igc_init_tx_empty_descriptor(tx_ring, empty, empty_info) < 0) + dev_kfree_skb_any(empty); +} + static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb, struct igc_ring *tx_ring) { @@ -1603,26 +1623,8 @@ static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb, skb->tstamp = ktime_set(0, 0); launch_time = igc_tx_launchtime(tx_ring, txtime, &first_flag, &insert_empty);
- if (insert_empty) { - struct igc_tx_buffer *empty_info; - struct sk_buff *empty; - void *data; - - empty_info = &tx_ring->tx_buffer_info[tx_ring->next_to_use]; - empty = alloc_skb(IGC_EMPTY_FRAME_SIZE, GFP_ATOMIC); - if (!empty) - goto done; - - data = skb_put(empty, IGC_EMPTY_FRAME_SIZE); - memset(data, 0, IGC_EMPTY_FRAME_SIZE); - - igc_tx_ctxtdesc(tx_ring, 0, false, 0, 0, 0); - - if (igc_init_tx_empty_descriptor(tx_ring, - empty, - empty_info) < 0) - dev_kfree_skb_any(empty); - } + if (insert_empty) + igc_insert_empty_packet(tx_ring);
done: /* record the location of the first descriptor for this packet */
On Wed, Feb 05, 2025 at 10:41:15AM +0800, Song Yoong Siang wrote:
Refactor the code for inserting an empty packet into a new function igc_insert_empty_packet(). This change extracts the logic for inserting an empty packet from igc_xmit_frame_ring() into a separate function, allowing it to be reused in future implementations, such as the XDP zero copy transmit function.
This patch introduces no functional changes.
Signed-off-by: Song Yoong Siang yoong.siang.song@intel.com
Your SoB should be last in the set of tags.
Reviewed-by: Faizal Rahim faizal.abdul.rahim@linux.intel.com
drivers/net/ethernet/intel/igc/igc_main.c | 42 ++++++++++++----------- 1 file changed, 22 insertions(+), 20 deletions(-)
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c index 21f318f12a8d..553d6d82af0d 100644 --- a/drivers/net/ethernet/intel/igc/igc_main.c +++ b/drivers/net/ethernet/intel/igc/igc_main.c @@ -1566,6 +1566,26 @@ static bool igc_request_tx_tstamp(struct igc_adapter *adapter, struct sk_buff *s return false; } +static void igc_insert_empty_packet(struct igc_ring *tx_ring) +{
- struct igc_tx_buffer *empty_info;
- struct sk_buff *empty;
- void *data;
- empty_info = &tx_ring->tx_buffer_info[tx_ring->next_to_use];
- empty = alloc_skb(IGC_EMPTY_FRAME_SIZE, GFP_ATOMIC);
- if (!empty)
return;- data = skb_put(empty, IGC_EMPTY_FRAME_SIZE);
- memset(data, 0, IGC_EMPTY_FRAME_SIZE);
- igc_tx_ctxtdesc(tx_ring, 0, false, 0, 0, 0);
- if (igc_init_tx_empty_descriptor(tx_ring, empty, empty_info) < 0)
dev_kfree_skb_any(empty);
I still don't like the fact igc_insert_empty_packet() doesn't communicate to caller whether it successfully produced descriptors or not.
Look at this from igc_xmit_frame_ring() POV: - at the beginning you peek at Tx ring whether there is required amount of descriptors free to be used - but then here's your additional routine which might consume two more descs and you are not aware of the status - then you continue to further produce descriptors assuming there is enough space in Tx ring
Right now igc_init_tx_empty_descriptor() returns -EBUSY when ring is full. How can that happen in the first place + what if it would *really* happen though? You just continue with your Tx flow.
What I'm trying to say here is, at least from correctness POV, you should take into the account two potential descriptors for launchtime feature when calling igc_maybe_stop_tx(). And igc_init_tx_empty_descriptor() should not really care about space in ring, it should be a caller's job to call it only when it will be sure it's safe to do so.
+}
static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb, struct igc_ring *tx_ring) { @@ -1603,26 +1623,8 @@ static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb, skb->tstamp = ktime_set(0, 0); launch_time = igc_tx_launchtime(tx_ring, txtime, &first_flag, &insert_empty);
- if (insert_empty) {
struct igc_tx_buffer *empty_info;struct sk_buff *empty;void *data;empty_info = &tx_ring->tx_buffer_info[tx_ring->next_to_use];empty = alloc_skb(IGC_EMPTY_FRAME_SIZE, GFP_ATOMIC);if (!empty)goto done;data = skb_put(empty, IGC_EMPTY_FRAME_SIZE);memset(data, 0, IGC_EMPTY_FRAME_SIZE);igc_tx_ctxtdesc(tx_ring, 0, false, 0, 0, 0);if (igc_init_tx_empty_descriptor(tx_ring,empty,empty_info) < 0)dev_kfree_skb_any(empty);- }
- if (insert_empty)
igc_insert_empty_packet(tx_ring);done: /* record the location of the first descriptor for this packet */ -- 2.34.1
On Wednesday, February 5, 2025 8:31 PM, Fijalkowski, Maciej maciej.fijalkowski@intel.com wrote:
On Wed, Feb 05, 2025 at 10:41:15AM +0800, Song Yoong Siang wrote:
Refactor the code for inserting an empty packet into a new function igc_insert_empty_packet(). This change extracts the logic for inserting an empty packet from igc_xmit_frame_ring() into a separate function, allowing it to be reused in future implementations, such as the XDP zero copy transmit function.
This patch introduces no functional changes.
Signed-off-by: Song Yoong Siang yoong.siang.song@intel.com
Your SoB should be last in the set of tags.
Noted. Thanks for the tips.
Reviewed-by: Faizal Rahim faizal.abdul.rahim@linux.intel.com
drivers/net/ethernet/intel/igc/igc_main.c | 42 ++++++++++++----------- 1 file changed, 22 insertions(+), 20 deletions(-)
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c
b/drivers/net/ethernet/intel/igc/igc_main.c
index 21f318f12a8d..553d6d82af0d 100644 --- a/drivers/net/ethernet/intel/igc/igc_main.c +++ b/drivers/net/ethernet/intel/igc/igc_main.c @@ -1566,6 +1566,26 @@ static bool igc_request_tx_tstamp(struct igc_adapter
*adapter, struct sk_buff *s
return false; }
+static void igc_insert_empty_packet(struct igc_ring *tx_ring) +{
- struct igc_tx_buffer *empty_info;
- struct sk_buff *empty;
- void *data;
- empty_info = &tx_ring->tx_buffer_info[tx_ring->next_to_use];
- empty = alloc_skb(IGC_EMPTY_FRAME_SIZE, GFP_ATOMIC);
- if (!empty)
return;- data = skb_put(empty, IGC_EMPTY_FRAME_SIZE);
- memset(data, 0, IGC_EMPTY_FRAME_SIZE);
- igc_tx_ctxtdesc(tx_ring, 0, false, 0, 0, 0);
- if (igc_init_tx_empty_descriptor(tx_ring, empty, empty_info) < 0)
dev_kfree_skb_any(empty);I still don't like the fact igc_insert_empty_packet() doesn't communicate to caller whether it successfully produced descriptors or not.
Look at this from igc_xmit_frame_ring() POV:
- at the beginning you peek at Tx ring whether there is required amount of
descriptors free to be used
- but then here's your additional routine which might consume two more
descs and you are not aware of the status
- then you continue to further produce descriptors assuming there is
enough space in Tx ring
Right now igc_init_tx_empty_descriptor() returns -EBUSY when ring is full. How can that happen in the first place + what if it would *really* happen though? You just continue with your Tx flow.
What I'm trying to say here is, at least from correctness POV, you should take into the account two potential descriptors for launchtime feature when calling igc_maybe_stop_tx(). And igc_init_tx_empty_descriptor() should not really care about space in ring, it should be a caller's job to call it only when it will be sure it's safe to do so.
Agree with you.
In db0b124f02ba ("igc: Enhance Qbv scheduling by using first flag bit"), the 2 descriptors needed by empty packet is already taken into consideration by changing igc_maybe_stop_tx(tx_ring, count + 3) to igc_maybe_stop_tx(tx_ring, count + 5), so not enough ring space issue will not happened. However, the comment session is not updated, maybe i can update it in next version of this patch as below:
@@ -1586,6 +1608,7 @@ static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb, * + 1 desc for skb_headlen/IGC_MAX_DATA_PER_TXD, * + 2 desc gap to keep tail from touching head, * + 1 desc for context descriptor, + * + 2 desc for inserting an empty packet for launch time, * otherwise try next time */ for (f = 0; f < skb_shinfo(skb)->nr_frags; f++)
Since number of descriptor needed is guaranteed. I will take out the igc_desc_unused() checking in igc_init_tx_empty_descriptor(). However, empty packet insertion might fail due to skb allocation failure and DMA mapping error. How about i make sure skb allocation and DMA mapping working, before proceed to fill in igc_tx_buffer, context desc, and data desc? IMHO, because these two errors are unlikely to happen, print a kernel warning msg should be enough.
@@ -1108,20 +1108,12 @@ static int igc_init_empty_frame(struct igc_ring *ring, return 0; }
-static int igc_init_tx_empty_descriptor(struct igc_ring *ring, +static void igc_init_tx_empty_descriptor(struct igc_ring *ring, struct sk_buff *skb, struct igc_tx_buffer *first) { union igc_adv_tx_desc *desc; u32 cmd_type, olinfo_status; - int err; - - if (!igc_desc_unused(ring)) - return -EBUSY; - - err = igc_init_empty_frame(ring, first, skb); - if (err) - return err;
cmd_type = IGC_ADVTXD_DTYP_DATA | IGC_ADVTXD_DCMD_DEXT | IGC_ADVTXD_DCMD_IFCS | IGC_TXD_DCMD | @@ -1140,8 +1132,6 @@ static int igc_init_tx_empty_descriptor(struct igc_ring *ring, ring->next_to_use++; if (ring->next_to_use == ring->count) ring->next_to_use = 0; - - return 0; }
#define IGC_EMPTY_FRAME_SIZE 60 @@ -1567,6 +1557,38 @@ static bool igc_request_tx_tstamp(struct igc_adapter *adapter, struct sk_buff *s return false; }
+static void igc_insert_empty_packet(struct igc_ring *tx_ring) +{ + struct igc_tx_buffer *empty_info; + struct sk_buff *empty; + void *data; + + empty_info = &tx_ring->tx_buffer_info[tx_ring->next_to_use]; + empty = alloc_skb(IGC_EMPTY_FRAME_SIZE, GFP_ATOMIC); + if (unlikely(!empty)) { + netdev_warn(tx_ring->netdev, + "Fail to alloc skb for empty packet\n"); + return; + } + + data = skb_put(empty, IGC_EMPTY_FRAME_SIZE); + memset(data, 0, IGC_EMPTY_FRAME_SIZE); + + /* Prepare DMA mapping and Tx buffer information */ + if (unlikely(igc_init_empty_frame(tx_ring, empty_info, empty))) { + dev_kfree_skb_any(empty); + netdev_warn(tx_ring->netdev, + "Fail to map DMA for empty packet\n"); + return; + } + + /* Prepare context descriptor for empty packet */ + igc_tx_ctxtdesc(tx_ring, 0, false, 0, 0, 0); + + /* Prepare data descriptor for empty packet */ + igc_init_tx_empty_descriptor(tx_ring, empty, empty_info); +} + static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb, struct igc_ring *tx_ring) {
Are above codes resolve your concern? If yes, i can test and add them into this patch in next version submission.
Thanks & Regards Siang
On Wed, Feb 05, 2025 at 03:43:19PM +0100, Song, Yoong Siang wrote:
On Wednesday, February 5, 2025 8:31 PM, Fijalkowski, Maciej maciej.fijalkowski@intel.com wrote:
On Wed, Feb 05, 2025 at 10:41:15AM +0800, Song Yoong Siang wrote:
Refactor the code for inserting an empty packet into a new function igc_insert_empty_packet(). This change extracts the logic for inserting an empty packet from igc_xmit_frame_ring() into a separate function, allowing it to be reused in future implementations, such as the XDP zero copy transmit function.
This patch introduces no functional changes.
Signed-off-by: Song Yoong Siang yoong.siang.song@intel.com
Your SoB should be last in the set of tags.
Noted. Thanks for the tips.
Reviewed-by: Faizal Rahim faizal.abdul.rahim@linux.intel.com
drivers/net/ethernet/intel/igc/igc_main.c | 42 ++++++++++++----------- 1 file changed, 22 insertions(+), 20 deletions(-)
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c
b/drivers/net/ethernet/intel/igc/igc_main.c
index 21f318f12a8d..553d6d82af0d 100644 --- a/drivers/net/ethernet/intel/igc/igc_main.c +++ b/drivers/net/ethernet/intel/igc/igc_main.c @@ -1566,6 +1566,26 @@ static bool igc_request_tx_tstamp(struct igc_adapter
*adapter, struct sk_buff *s
return false; }
+static void igc_insert_empty_packet(struct igc_ring *tx_ring) +{
- struct igc_tx_buffer *empty_info;
- struct sk_buff *empty;
- void *data;
- empty_info = &tx_ring->tx_buffer_info[tx_ring->next_to_use];
- empty = alloc_skb(IGC_EMPTY_FRAME_SIZE, GFP_ATOMIC);
- if (!empty)
return;- data = skb_put(empty, IGC_EMPTY_FRAME_SIZE);
- memset(data, 0, IGC_EMPTY_FRAME_SIZE);
- igc_tx_ctxtdesc(tx_ring, 0, false, 0, 0, 0);
- if (igc_init_tx_empty_descriptor(tx_ring, empty, empty_info) < 0)
dev_kfree_skb_any(empty);I still don't like the fact igc_insert_empty_packet() doesn't communicate to caller whether it successfully produced descriptors or not.
Look at this from igc_xmit_frame_ring() POV:
- at the beginning you peek at Tx ring whether there is required amount of
descriptors free to be used
- but then here's your additional routine which might consume two more
descs and you are not aware of the status
- then you continue to further produce descriptors assuming there is
enough space in Tx ring
Right now igc_init_tx_empty_descriptor() returns -EBUSY when ring is full. How can that happen in the first place + what if it would *really* happen though? You just continue with your Tx flow.
What I'm trying to say here is, at least from correctness POV, you should take into the account two potential descriptors for launchtime feature when calling igc_maybe_stop_tx(). And igc_init_tx_empty_descriptor() should not really care about space in ring, it should be a caller's job to call it only when it will be sure it's safe to do so.
Agree with you.
In db0b124f02ba ("igc: Enhance Qbv scheduling by using first flag bit"), the 2 descriptors needed by empty packet is already taken into consideration by changing igc_maybe_stop_tx(tx_ring, count + 3) to igc_maybe_stop_tx(tx_ring, count + 5), so not enough ring space issue will not happened. However, the comment session is not updated, maybe i can update it in next version of this patch as below:
@@ -1586,6 +1608,7 @@ static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb, * + 1 desc for skb_headlen/IGC_MAX_DATA_PER_TXD, * + 2 desc gap to keep tail from touching head, * + 1 desc for context descriptor,
* + 2 desc for inserting an empty packet for launch time, * otherwise try next time */ for (f = 0; f < skb_shinfo(skb)->nr_frags; f++)
Ahh good then, I didn't pay enough attention to comment. So it meant that first two entries from comment were covered by @count and 2 desc gap + 1 ctxt desc were behind '3', previously.
Since number of descriptor needed is guaranteed. I will take out the igc_desc_unused() checking in igc_init_tx_empty_descriptor().
Yes
However, empty packet insertion might fail due to skb allocation failure and DMA mapping error. How about i make sure skb allocation and DMA mapping working, before proceed to fill in igc_tx_buffer, context desc, and data desc? IMHO, because these two errors are unlikely to happen, print a kernel warning msg should be enough.
@@ -1108,20 +1108,12 @@ static int igc_init_empty_frame(struct igc_ring *ring, return 0; }
-static int igc_init_tx_empty_descriptor(struct igc_ring *ring, +static void igc_init_tx_empty_descriptor(struct igc_ring *ring, struct sk_buff *skb, struct igc_tx_buffer *first) { union igc_adv_tx_desc *desc; u32 cmd_type, olinfo_status;
int err;if (!igc_desc_unused(ring))return -EBUSY;err = igc_init_empty_frame(ring, first, skb);if (err)return err; cmd_type = IGC_ADVTXD_DTYP_DATA | IGC_ADVTXD_DCMD_DEXT | IGC_ADVTXD_DCMD_IFCS | IGC_TXD_DCMD |@@ -1140,8 +1132,6 @@ static int igc_init_tx_empty_descriptor(struct igc_ring *ring, ring->next_to_use++; if (ring->next_to_use == ring->count) ring->next_to_use = 0;
return 0;}
#define IGC_EMPTY_FRAME_SIZE 60 @@ -1567,6 +1557,38 @@ static bool igc_request_tx_tstamp(struct igc_adapter *adapter, struct sk_buff *s return false; }
+static void igc_insert_empty_packet(struct igc_ring *tx_ring) +{
struct igc_tx_buffer *empty_info;struct sk_buff *empty;void *data;empty_info = &tx_ring->tx_buffer_info[tx_ring->next_to_use];empty = alloc_skb(IGC_EMPTY_FRAME_SIZE, GFP_ATOMIC);if (unlikely(!empty)) {netdev_warn(tx_ring->netdev,"Fail to alloc skb for empty packet\n");
That should be at least ratelimited I think, but what really is the problem to make these routines return status and check them on caller side?
return;}data = skb_put(empty, IGC_EMPTY_FRAME_SIZE);memset(data, 0, IGC_EMPTY_FRAME_SIZE);/* Prepare DMA mapping and Tx buffer information */if (unlikely(igc_init_empty_frame(tx_ring, empty_info, empty))) {dev_kfree_skb_any(empty);netdev_warn(tx_ring->netdev,"Fail to map DMA for empty packet\n");return;}/* Prepare context descriptor for empty packet */igc_tx_ctxtdesc(tx_ring, 0, false, 0, 0, 0);/* Prepare data descriptor for empty packet */igc_init_tx_empty_descriptor(tx_ring, empty, empty_info);+}
static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb, struct igc_ring *tx_ring) {
Are above codes resolve your concern? If yes, i can test and add them into this patch in next version submission.
Thanks & Regards Siang
On Thursday, February 6, 2025 12:08 AM, Fijalkowski, Maciej maciej.fijalkowski@intel.com wrote:
On Wed, Feb 05, 2025 at 03:43:19PM +0100, Song, Yoong Siang wrote:
On Wednesday, February 5, 2025 8:31 PM, Fijalkowski, Maciejmaciej.fijalkowski@intel.com wrote:
On Wed, Feb 05, 2025 at 10:41:15AM +0800, Song Yoong Siang wrote:
Refactor the code for inserting an empty packet into a new function igc_insert_empty_packet(). This change extracts the logic for inserting an empty packet from igc_xmit_frame_ring() into a separate function, allowing it to be reused in future implementations, such as the XDP zero copy transmit function.
This patch introduces no functional changes.
Signed-off-by: Song Yoong Siang yoong.siang.song@intel.com
Your SoB should be last in the set of tags.
Noted. Thanks for the tips.
Reviewed-by: Faizal Rahim faizal.abdul.rahim@linux.intel.com
drivers/net/ethernet/intel/igc/igc_main.c | 42 ++++++++++++----------- 1 file changed, 22 insertions(+), 20 deletions(-)
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c
b/drivers/net/ethernet/intel/igc/igc_main.c
index 21f318f12a8d..553d6d82af0d 100644 --- a/drivers/net/ethernet/intel/igc/igc_main.c +++ b/drivers/net/ethernet/intel/igc/igc_main.c @@ -1566,6 +1566,26 @@ static bool igc_request_tx_tstamp(struct igc_adapter
*adapter, struct sk_buff *s
return false; }
+static void igc_insert_empty_packet(struct igc_ring *tx_ring) +{
- struct igc_tx_buffer *empty_info;
- struct sk_buff *empty;
- void *data;
- empty_info = &tx_ring->tx_buffer_info[tx_ring->next_to_use];
- empty = alloc_skb(IGC_EMPTY_FRAME_SIZE, GFP_ATOMIC);
- if (!empty)
return;- data = skb_put(empty, IGC_EMPTY_FRAME_SIZE);
- memset(data, 0, IGC_EMPTY_FRAME_SIZE);
- igc_tx_ctxtdesc(tx_ring, 0, false, 0, 0, 0);
- if (igc_init_tx_empty_descriptor(tx_ring, empty, empty_info) < 0)
dev_kfree_skb_any(empty);I still don't like the fact igc_insert_empty_packet() doesn't communicate to caller whether it successfully produced descriptors or not.
Look at this from igc_xmit_frame_ring() POV:
- at the beginning you peek at Tx ring whether there is required amount of
descriptors free to be used
- but then here's your additional routine which might consume two more
descs and you are not aware of the status
- then you continue to further produce descriptors assuming there is
enough space in Tx ring
Right now igc_init_tx_empty_descriptor() returns -EBUSY when ring is full. How can that happen in the first place + what if it would *really* happen though? You just continue with your Tx flow.
What I'm trying to say here is, at least from correctness POV, you should take into the account two potential descriptors for launchtime feature when calling igc_maybe_stop_tx(). And igc_init_tx_empty_descriptor() should not really care about space in ring, it should be a caller's job to call it only when it will be sure it's safe to do so.
Agree with you.
In db0b124f02ba ("igc: Enhance Qbv scheduling by using first flag bit"), the 2 descriptors needed by empty packet is already taken into consideration by changing igc_maybe_stop_tx(tx_ring, count + 3) to igc_maybe_stop_tx(tx_ring, count + 5), so not enough ring space issue will not happened. However, the comment session is not updated, maybe i can update it in next version of this patch as below:
@@ -1586,6 +1608,7 @@ static netdev_tx_t igc_xmit_frame_ring(struct sk_buff
*skb,
* + 1 desc for skb_headlen/IGC_MAX_DATA_PER_TXD, * + 2 desc gap to keep tail from touching head, * + 1 desc for context descriptor,
* + 2 desc for inserting an empty packet for launch time, * otherwise try next time */ for (f = 0; f < skb_shinfo(skb)->nr_frags; f++)Ahh good then, I didn't pay enough attention to comment. So it meant that first two entries from comment were covered by @count and 2 desc gap + 1 ctxt desc were behind '3', previously.
Yes, you are right.
Since number of descriptor needed is guaranteed. I will take out the igc_desc_unused() checking in igc_init_tx_empty_descriptor().
Yes
However, empty packet insertion might fail due to skb allocation failure and DMA mapping error. How about i make sure skb allocation and DMA mapping working, before proceed to fill in igc_tx_buffer, context desc, and data desc? IMHO, because these two errors are unlikely to happen, print a kernel warning msg should be enough.
@@ -1108,20 +1108,12 @@ static int igc_init_empty_frame(struct igc_ring *ring, return 0; }
-static int igc_init_tx_empty_descriptor(struct igc_ring *ring, +static void igc_init_tx_empty_descriptor(struct igc_ring *ring, struct sk_buff *skb, struct igc_tx_buffer *first) { union igc_adv_tx_desc *desc; u32 cmd_type, olinfo_status;
int err;if (!igc_desc_unused(ring))return -EBUSY;err = igc_init_empty_frame(ring, first, skb);if (err)return err; cmd_type = IGC_ADVTXD_DTYP_DATA | IGC_ADVTXD_DCMD_DEXT | IGC_ADVTXD_DCMD_IFCS | IGC_TXD_DCMD |@@ -1140,8 +1132,6 @@ static int igc_init_tx_empty_descriptor(struct igc_ring
*ring,
ring->next_to_use++; if (ring->next_to_use == ring->count) ring->next_to_use = 0;
return 0;}
#define IGC_EMPTY_FRAME_SIZE 60 @@ -1567,6 +1557,38 @@ static bool igc_request_tx_tstamp(struct igc_adapter
*adapter, struct sk_buff *s
return false;}
+static void igc_insert_empty_packet(struct igc_ring *tx_ring) +{
struct igc_tx_buffer *empty_info;struct sk_buff *empty;void *data;empty_info = &tx_ring->tx_buffer_info[tx_ring->next_to_use];empty = alloc_skb(IGC_EMPTY_FRAME_SIZE, GFP_ATOMIC);if (unlikely(!empty)) {netdev_warn(tx_ring->netdev,"Fail to alloc skb for empty packet\n");That should be at least ratelimited I think, but what really is the
No problem, I will add net_ratelimit() checking.
problem to make these routines return status and check them on caller side?
Ok, I will add return value and handle the case where the insertion of an empty frame fails and explain the reason behind.
Thanks & Regards Siang
Enable Launch Time Control (LTC) support for XDP zero copy via XDP Tx metadata framework.
This patch has been tested with tools/testing/selftests/bpf/xdp_hw_metadata on Intel I225-LM Ethernet controller. Below are the test steps and result.
Test 1: Send a single packet with the launch time set to 1 s in the future.
Test steps: 1. On the DUT, start the xdp_hw_metadata selftest application: $ sudo ./xdp_hw_metadata enp2s0 -l 1000000000 -L 1
2. On the Link Partner, send a UDP packet with VLAN priority 1 to port 9091 of the DUT.
Result: When the launch time is set to 1 s in the future, the delta between the launch time and the transmit hardware timestamp is 0.016 us, as shown in printout of the xdp_hw_metadata application below. 0x562ff5dc8880: rx_desc[4]->addr=84110 addr=84110 comp_addr=84110 EoP rx_hash: 0xE343384 with RSS type:0x1 HW RX-time: 1734578015467548904 (sec:1734578015.4675) delta to User RX-time sec:0.0002 (183.103 usec) XDP RX-time: 1734578015467651698 (sec:1734578015.4677) delta to User RX-time sec:0.0001 (80.309 usec) No rx_vlan_tci or rx_vlan_proto, err=-95 0x562ff5dc8880: ping-pong with csum=561c (want c7dd) csum_start=34 csum_offset=6 HW RX-time: 1734578015467548904 (sec:1734578015.4675) delta to HW Launch-time sec:1.0000 (1000000.000 usec) 0x562ff5dc8880: complete tx idx=4 addr=4018 HW Launch-time: 1734578016467548904 (sec:1734578016.4675) delta to HW TX-complete-time sec:0.0000 (0.016 usec) HW TX-complete-time: 1734578016467548920 (sec:1734578016.4675) delta to User TX-complete-time sec:0.0000 (32.546 usec) XDP RX-time: 1734578015467651698 (sec:1734578015.4677) delta to User TX-complete-time sec:0.9999 (999929.768 usec) HW RX-time: 1734578015467548904 (sec:1734578015.4675) delta to HW TX-complete-time sec:1.0000 (1000000.016 usec) 0x562ff5dc8880: complete rx idx=132 addr=84110
Test 2: Send 1000 packets with a 10 ms interval and the launch time set to 500 us in the future.
Test steps: 1. On the DUT, start the xdp_hw_metadata selftest application: $ sudo chrt -f 99 ./xdp_hw_metadata enp2s0 -l 500000 -L 1 > \ /dev/shm/result.log
2. On the Link Partner, send 1000 UDP packets with a 10 ms interval and VLAN priority 1 to port 9091 of the DUT.
Result: When the launch time is set to 500 us in the future, the average delta between the launch time and the transmit hardware timestamp is 0.016 us, as shown in the analysis of /dev/shm/result.log below. The XDP launch time works correctly in sending 1000 packets continuously. Min delta: 0.005 us Avr delta: 0.016 us Max delta: 0.031 us Total packets forwarded: 1000
Signed-off-by: Song Yoong Siang yoong.siang.song@intel.com --- drivers/net/ethernet/intel/igc/igc.h | 1 + drivers/net/ethernet/intel/igc/igc_main.c | 52 ++++++++++++++++++++++- 2 files changed, 51 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h index b8111ad9a9a8..cd1d7b6c1782 100644 --- a/drivers/net/ethernet/intel/igc/igc.h +++ b/drivers/net/ethernet/intel/igc/igc.h @@ -579,6 +579,7 @@ struct igc_metadata_request { struct xsk_tx_metadata *meta; struct igc_ring *tx_ring; u32 cmd_type; + u16 used_desc; };
struct igc_q_vector { diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c index 553d6d82af0d..a4ec487da701 100644 --- a/drivers/net/ethernet/intel/igc/igc_main.c +++ b/drivers/net/ethernet/intel/igc/igc_main.c @@ -2954,9 +2954,39 @@ static u64 igc_xsk_fill_timestamp(void *_priv) return *(u64 *)_priv; }
+static void igc_xsk_request_launch_time(u64 launch_time, void *_priv) +{ + struct igc_metadata_request *meta_req = _priv; + struct igc_ring *tx_ring = meta_req->tx_ring; + __le32 launch_time_offset; + bool insert_empty = false; + bool first_flag = false; + + if (!tx_ring->launchtime_enable) + return; + + launch_time_offset = igc_tx_launchtime(tx_ring, + ns_to_ktime(launch_time), + &first_flag, &insert_empty); + if (insert_empty) { + igc_insert_empty_packet(tx_ring); + meta_req->tx_buffer = + &tx_ring->tx_buffer_info[tx_ring->next_to_use]; + /* Inserting an empty packet requires two descriptors: + * one data descriptor and one context descriptor. + */ + meta_req->used_desc += 2; + } + + /* Use one context descriptor to specify launch time and first flag. */ + igc_tx_ctxtdesc(tx_ring, launch_time_offset, first_flag, 0, 0, 0); + meta_req->used_desc += 1; +} + const struct xsk_tx_metadata_ops igc_xsk_tx_metadata_ops = { .tmo_request_timestamp = igc_xsk_request_timestamp, .tmo_fill_timestamp = igc_xsk_fill_timestamp, + .tmo_request_launch_time = igc_xsk_request_launch_time, };
static void igc_xdp_xmit_zc(struct igc_ring *ring) @@ -2979,7 +3009,13 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring) ntu = ring->next_to_use; budget = igc_desc_unused(ring);
- while (xsk_tx_peek_desc(pool, &xdp_desc) && budget--) { + /* Packets with launch time require one data descriptor and one context + * descriptor. When the launch time falls into the next Qbv cycle, we + * may need to insert an empty packet, which requires two more + * descriptors. Therefore, to be safe, we always ensure we have at least + * 4 descriptors available. + */ + while (xsk_tx_peek_desc(pool, &xdp_desc) && budget >= 4) { struct igc_metadata_request meta_req; struct xsk_tx_metadata *meta = NULL; struct igc_tx_buffer *bi; @@ -3000,9 +3036,19 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring) meta_req.tx_ring = ring; meta_req.tx_buffer = bi; meta_req.meta = meta; + meta_req.used_desc = 0; xsk_tx_metadata_request(meta, &igc_xsk_tx_metadata_ops, &meta_req);
+ /* xsk_tx_metadata_request() may have updated next_to_use */ + ntu = ring->next_to_use; + + /* xsk_tx_metadata_request() may have updated Tx buffer info */ + bi = meta_req.tx_buffer; + + /* xsk_tx_metadata_request() may use a few descriptors */ + budget -= meta_req.used_desc; + tx_desc = IGC_TX_DESC(ring, ntu); tx_desc->read.cmd_type_len = cpu_to_le32(meta_req.cmd_type); tx_desc->read.olinfo_status = cpu_to_le32(olinfo_status); @@ -3020,9 +3066,11 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring) ntu++; if (ntu == ring->count) ntu = 0; + + ring->next_to_use = ntu; + budget--; }
- ring->next_to_use = ntu; if (tx_desc) { igc_flush_tx_descriptors(ring); xsk_tx_release(pool);
linux-kselftest-mirror@lists.linaro.org
-
Maciej Fijalkowski -
Song Yoong Siang -
Song, Yoong Siang