From: Long Li longli@microsoft.com
It's inefficient to ring the doorbell page every time a WQE is posted to the received queue.
Move the code for ringing doorbell page to where after we have posted all WQEs to the receive queue during a callback from napi_poll().
Tests showed no regression in network latency benchmarks.
Cc: stable@vger.kernel.org Fixes: ca9c54d2d6a5 ("net: mana: Add a driver for Microsoft Azure Network Adapter (MANA)") Signed-off-by: Long Li longli@microsoft.com --- Change log: v2: Check for comp_read > 0 as it might be negative on completion error. Set rq.wqe_cnt to 0 according to BNIC spec.
drivers/net/ethernet/microsoft/mana/gdma_main.c | 5 ++++- drivers/net/ethernet/microsoft/mana/mana_en.c | 10 ++++++++-- 2 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/drivers/net/ethernet/microsoft/mana/gdma_main.c b/drivers/net/ethernet/microsoft/mana/gdma_main.c index 8f3f78b68592..ef11d09a3655 100644 --- a/drivers/net/ethernet/microsoft/mana/gdma_main.c +++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c @@ -300,8 +300,11 @@ static void mana_gd_ring_doorbell(struct gdma_context *gc, u32 db_index,
void mana_gd_wq_ring_doorbell(struct gdma_context *gc, struct gdma_queue *queue) { + /* BNIC Spec specifies that client should set 0 for rq.wqe_cnt + * This value is not used in sq + */ mana_gd_ring_doorbell(gc, queue->gdma_dev->doorbell, queue->type, - queue->id, queue->head * GDMA_WQE_BU_SIZE, 1); + queue->id, queue->head * GDMA_WQE_BU_SIZE, 0); }
void mana_gd_ring_cq(struct gdma_queue *cq, u8 arm_bit) diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c index cd4d5ceb9f2d..1d8abe63fcb8 100644 --- a/drivers/net/ethernet/microsoft/mana/mana_en.c +++ b/drivers/net/ethernet/microsoft/mana/mana_en.c @@ -1383,8 +1383,8 @@ static void mana_post_pkt_rxq(struct mana_rxq *rxq)
recv_buf_oob = &rxq->rx_oobs[curr_index];
- err = mana_gd_post_and_ring(rxq->gdma_rq, &recv_buf_oob->wqe_req, - &recv_buf_oob->wqe_inf); + err = mana_gd_post_work_request(rxq->gdma_rq, &recv_buf_oob->wqe_req, + &recv_buf_oob->wqe_inf); if (WARN_ON_ONCE(err)) return;
@@ -1654,6 +1654,12 @@ static void mana_poll_rx_cq(struct mana_cq *cq) mana_process_rx_cqe(rxq, cq, &comp[i]); }
+ if (comp_read > 0) { + struct gdma_context *gc = rxq->gdma_rq->gdma_dev->gdma_context; + + mana_gd_wq_ring_doorbell(gc, rxq->gdma_rq); + } + if (rxq->xdp_flush) xdp_do_flush(); }
-----Original Message----- From: longli@linuxonhyperv.com longli@linuxonhyperv.com Sent: Thursday, June 22, 2023 12:23 PM To: Jason Gunthorpe jgg@ziepe.ca; Leon Romanovsky leon@kernel.org; Ajay Sharma sharmaajay@microsoft.com; Dexuan Cui decui@microsoft.com; KY Srinivasan kys@microsoft.com; Haiyang Zhang haiyangz@microsoft.com; Wei Liu wei.liu@kernel.org; David S. Miller davem@davemloft.net; Eric Dumazet edumazet@google.com; Jakub Kicinski kuba@kernel.org; Paolo Abeni pabeni@redhat.com Cc: linux-rdma@vger.kernel.org; linux-hyperv@vger.kernel.org; netdev@vger.kernel.org; linux-kernel@vger.kernel.org; Long Li longli@microsoft.com; stable@vger.kernel.org Subject: [PATCH v2] net: mana: Batch ringing RX queue doorbell on receiving packets
From: Long Li longli@microsoft.com
It's inefficient to ring the doorbell page every time a WQE is posted to the received queue.
Move the code for ringing doorbell page to where after we have posted all WQEs to the receive queue during a callback from napi_poll().
Tests showed no regression in network latency benchmarks.
Cc: stable@vger.kernel.org Fixes: ca9c54d2d6a5 ("net: mana: Add a driver for Microsoft Azure Network Adapter (MANA)") Signed-off-by: Long Li longli@microsoft.com
Reviewed-by: Haiyang Zhang haiyangz@microsoft.com
From: longli@linuxonhyperv.com Sent: Thursday, June 22, 2023 9:23 AM ...
It's inefficient to ring the doorbell page every time a WQE is posted to the received queue.
Move the code for ringing doorbell page to where after we have posted all WQEs to the receive queue during a callback from napi_poll().
Tests showed no regression in network latency benchmarks.
Cc: stable@vger.kernel.org Fixes: ca9c54d2d6a5 ("net: mana: Add a driver for Microsoft Azure Network Adapter (MANA)") Signed-off-by: Long Li longli@microsoft.com
Reviewed-by: Dexuan Cui decui@microsoft.com
On Thu, 22 Jun 2023 09:22:36 -0700 longli@linuxonhyperv.com wrote:
It's inefficient to ring the doorbell page every time a WQE is posted to the received queue.
Move the code for ringing doorbell page to where after we have posted all WQEs to the receive queue during a callback from napi_poll().
Tests showed no regression in network latency benchmarks.
Cc: stable@vger.kernel.org Fixes: ca9c54d2d6a5 ("net: mana: Add a driver for Microsoft Azure Network Adapter (MANA)")
If this is supposed to be a fix, you need to clearly explain what the performance loss was, so that backporters can make an informed decision.
drivers/net/ethernet/microsoft/mana/gdma_main.c | 5 ++++- drivers/net/ethernet/microsoft/mana/mana_en.c | 10 ++++++++-- 2 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/drivers/net/ethernet/microsoft/mana/gdma_main.c b/drivers/net/ethernet/microsoft/mana/gdma_main.c index 8f3f78b68592..ef11d09a3655 100644 --- a/drivers/net/ethernet/microsoft/mana/gdma_main.c +++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c @@ -300,8 +300,11 @@ static void mana_gd_ring_doorbell(struct gdma_context *gc, u32 db_index, void mana_gd_wq_ring_doorbell(struct gdma_context *gc, struct gdma_queue *queue) {
- /* BNIC Spec specifies that client should set 0 for rq.wqe_cnt
* This value is not used in sq*/
queue->id, queue->head * GDMA_WQE_BU_SIZE, 1);
queue->id, queue->head * GDMA_WQE_BU_SIZE, 0);}
This change needs to be explained in the commit message, or should be a separate patch.
Subject: Re: [PATCH v2] net: mana: Batch ringing RX queue doorbell on receiving packets
On Thu, 22 Jun 2023 09:22:36 -0700 longli@linuxonhyperv.com wrote:
It's inefficient to ring the doorbell page every time a WQE is posted to the received queue.
Move the code for ringing doorbell page to where after we have posted all WQEs to the receive queue during a callback from napi_poll().
Tests showed no regression in network latency benchmarks.
Cc: stable@vger.kernel.org Fixes: ca9c54d2d6a5 ("net: mana: Add a driver for Microsoft Azure Network Adapter (MANA)")
If this is supposed to be a fix, you need to clearly explain what the performance loss was, so that backporters can make an informed decision.
I'm sending v3 to include the details.
drivers/net/ethernet/microsoft/mana/gdma_main.c | 5 ++++- drivers/net/ethernet/microsoft/mana/mana_en.c | 10 ++++++++-- 2 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/drivers/net/ethernet/microsoft/mana/gdma_main.c b/drivers/net/ethernet/microsoft/mana/gdma_main.c index 8f3f78b68592..ef11d09a3655 100644 --- a/drivers/net/ethernet/microsoft/mana/gdma_main.c +++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c @@ -300,8 +300,11 @@ static void mana_gd_ring_doorbell(struct gdma_context *gc, u32 db_index,
void mana_gd_wq_ring_doorbell(struct gdma_context *gc, struct gdma_queue *queue) {
- /* BNIC Spec specifies that client should set 0 for rq.wqe_cnt
* This value is not used in sq*/type,
queue->id, queue->head * GDMA_WQE_BU_SIZE,1);
queue->id, queue->head * GDMA_WQE_BU_SIZE,0);
}
This change needs to be explained in the commit message, or should be a separate patch.
Will explain the change in the commit message.
Thanks, Long
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