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From 37f08d570a33040979908d4140e5f2a499cff4c0 Mon Sep 17 00:00:00 2001
From: Long Li <longli@microsoft.com>
Date: Mon, 17 Jul 2023 12:35:38 -0700
Subject: [PATCH 26/44] net: mana: Batch ringing RX queue doorbell on receiving
packets
It's inefficient to ring the doorbell page every time a WQE is posted to
the received queue. Excessive MMIO writes result in CPU spending more
time waiting on LOCK instructions (atomic operations), resulting in
poor scaling performance.
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().
With this change, tests showed an improvement from 120G/s to 160G/s on a
200G physical link, with 16 or 32 hardware queues.
Tests showed no regression in network latency benchmarks on single
connection.
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Long Li <longli@microsoft.com>
Link: https://lore.kernel.org/r/1689622539-5334-2-git-send-email-longli@linuxonhyperv.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
(cherry picked from commit da4e8648079eb6f26f3a88d8c34270a057e2bfe6)
Signed-off-by: Bastian Blank <waldi@debian.org>
---
drivers/net/ethernet/microsoft/mana/mana_en.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
index a1c8b3c9a1ef..d982af3093e8 100644
--- a/drivers/net/ethernet/microsoft/mana/mana_en.c
+++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
@@ -1392,8 +1392,8 @@ 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;
@@ -1665,6 +1665,12 @@ 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();
}
--
2.49.0
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