6.6-stable review patch. If anyone has any objections, please let me know.
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From: Adam Li adamli@os.amperecomputing.com
[ Upstream commit 12a686c2e761f1f1f6e6e2117a9ab9c6de2ac8a7 ]
This patch adds /proc/sys/net/core/mem_pcpu_rsv sysctl file, to make SK_MEMORY_PCPU_RESERV tunable.
Commit 3cd3399dd7a8 ("net: implement per-cpu reserves for memory_allocated") introduced per-cpu forward alloc cache:
"Implement a per-cpu cache of +1/-1 MB, to reduce number of changes to sk->sk_prot->memory_allocated, which would otherwise be cause of false sharing."
sk_prot->memory_allocated points to global atomic variable: atomic_long_t tcp_memory_allocated ____cacheline_aligned_in_smp;
If increasing the per-cpu cache size from 1MB to e.g. 16MB, changes to sk->sk_prot->memory_allocated can be further reduced. Performance may be improved on system with many cores.
Signed-off-by: Adam Li adamli@os.amperecomputing.com Reviewed-by: Christoph Lameter (Ampere) cl@linux.com Signed-off-by: David S. Miller davem@davemloft.net Stable-dep-of: 3584718cf2ec ("net: fix sk_memory_allocated_{add|sub} vs softirqs") Signed-off-by: Sasha Levin sashal@kernel.org --- Documentation/admin-guide/sysctl/net.rst | 5 +++++ include/net/sock.h | 5 +++-- net/core/sock.c | 1 + net/core/sysctl_net_core.c | 9 +++++++++ 4 files changed, 18 insertions(+), 2 deletions(-)
diff --git a/Documentation/admin-guide/sysctl/net.rst b/Documentation/admin-guide/sysctl/net.rst index 4877563241f3b..5f1748f33d9a2 100644 --- a/Documentation/admin-guide/sysctl/net.rst +++ b/Documentation/admin-guide/sysctl/net.rst @@ -205,6 +205,11 @@ Will increase power usage.
Default: 0 (off)
+mem_pcpu_rsv +------------ + +Per-cpu reserved forward alloc cache size in page units. Default 1MB per CPU. + rmem_default ------------
diff --git a/include/net/sock.h b/include/net/sock.h index 25780942ec8bf..4372a7225ae6a 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1458,6 +1458,7 @@ sk_memory_allocated(const struct sock *sk)
/* 1 MB per cpu, in page units */ #define SK_MEMORY_PCPU_RESERVE (1 << (20 - PAGE_SHIFT)) +extern int sysctl_mem_pcpu_rsv;
static inline void sk_memory_allocated_add(struct sock *sk, int amt) @@ -1466,7 +1467,7 @@ sk_memory_allocated_add(struct sock *sk, int amt)
preempt_disable(); local_reserve = __this_cpu_add_return(*sk->sk_prot->per_cpu_fw_alloc, amt); - if (local_reserve >= SK_MEMORY_PCPU_RESERVE) { + if (local_reserve >= READ_ONCE(sysctl_mem_pcpu_rsv)) { __this_cpu_sub(*sk->sk_prot->per_cpu_fw_alloc, local_reserve); atomic_long_add(local_reserve, sk->sk_prot->memory_allocated); } @@ -1480,7 +1481,7 @@ sk_memory_allocated_sub(struct sock *sk, int amt)
preempt_disable(); local_reserve = __this_cpu_sub_return(*sk->sk_prot->per_cpu_fw_alloc, amt); - if (local_reserve <= -SK_MEMORY_PCPU_RESERVE) { + if (local_reserve <= -READ_ONCE(sysctl_mem_pcpu_rsv)) { __this_cpu_sub(*sk->sk_prot->per_cpu_fw_alloc, local_reserve); atomic_long_add(local_reserve, sk->sk_prot->memory_allocated); } diff --git a/net/core/sock.c b/net/core/sock.c index 383e30fe79f41..1471c0a862b36 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -283,6 +283,7 @@ __u32 sysctl_rmem_max __read_mostly = SK_RMEM_MAX; EXPORT_SYMBOL(sysctl_rmem_max); __u32 sysctl_wmem_default __read_mostly = SK_WMEM_MAX; __u32 sysctl_rmem_default __read_mostly = SK_RMEM_MAX; +int sysctl_mem_pcpu_rsv __read_mostly = SK_MEMORY_PCPU_RESERVE;
/* Maximal space eaten by iovec or ancillary data plus some space */ int sysctl_optmem_max __read_mostly = sizeof(unsigned long)*(2*UIO_MAXIOV+512); diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c index 03f1edb948d7d..373b5b2231c49 100644 --- a/net/core/sysctl_net_core.c +++ b/net/core/sysctl_net_core.c @@ -30,6 +30,7 @@ static int int_3600 = 3600; static int min_sndbuf = SOCK_MIN_SNDBUF; static int min_rcvbuf = SOCK_MIN_RCVBUF; static int max_skb_frags = MAX_SKB_FRAGS; +static int min_mem_pcpu_rsv = SK_MEMORY_PCPU_RESERVE;
static int net_msg_warn; /* Unused, but still a sysctl */
@@ -407,6 +408,14 @@ static struct ctl_table net_core_table[] = { .proc_handler = proc_dointvec_minmax, .extra1 = &min_rcvbuf, }, + { + .procname = "mem_pcpu_rsv", + .data = &sysctl_mem_pcpu_rsv, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &min_mem_pcpu_rsv, + }, { .procname = "dev_weight", .data = &weight_p,