From 821eba962d95806beb0440742c4062a9da8a386b Mon Sep 17 00:00:00 2001 From: Eric Dumazet <edumazet@google.com> Date: Tue, 28 Mar 2023 23:50:20 +0000 Subject: [PATCH] net: optimize napi_schedule_rps() Based on initial patch from Jason Xing. Idea is to not raise NET_RX_SOFTIRQ from napi_schedule_rps() when we queued a packet into another cpu backlog. We can do this only in the context of us being called indirectly from net_rx_action(), to have the guarantee our rps_ipi_list will be processed before we exit from net_rx_action(). Link: https://lore.kernel.org/lkml/20230325152417.5403-1-kerneljasonxing@gmail.com/ Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Jason Xing <kernelxing@tencent.com> Reviewed-by: Jason Xing <kerneljasonxing@gmail.com> Tested-by: Jason Xing <kerneljasonxing@gmail.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com> --- net/core/dev.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 15331edbacf4..f34ce93f2f02 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4587,8 +4587,6 @@ static void trigger_rx_softirq(void *data) * * - If this is another cpu queue, link it to our rps_ipi_list, * and make sure we will process rps_ipi_list from net_rx_action(). - * As we do not know yet if we are called from net_rx_action(), - * we have to raise NET_RX_SOFTIRQ. This might change in the future. * * - If this is our own queue, NAPI schedule our backlog. * Note that this also raises NET_RX_SOFTIRQ. @@ -4602,7 +4600,11 @@ static void napi_schedule_rps(struct softnet_data *sd) sd->rps_ipi_next = mysd->rps_ipi_list; mysd->rps_ipi_list = sd; - __raise_softirq_irqoff(NET_RX_SOFTIRQ); + /* If not called from net_rx_action() + * we have to raise NET_RX_SOFTIRQ. + */ + if (!mysd->in_net_rx_action) + __raise_softirq_irqoff(NET_RX_SOFTIRQ); return; } #endif /* CONFIG_RPS */ -- 2.42.0