From 10e16692d53112653f404a817e5dcc66540e8b98 Mon Sep 17 00:00:00 2001 From: CKI Backport Bot Date: Fri, 7 Feb 2025 13:57:37 +0000 Subject: [PATCH] af_packet: do not call packet_read_pending() from tpacket_destruct_skb() JIRA: https://issues.redhat.com/browse/RHEL-78307 commit 581073f626e387d3e7eed55c48c8495584ead7ba Author: Eric Dumazet Date: Wed May 15 16:33:58 2024 +0000 af_packet: do not call packet_read_pending() from tpacket_destruct_skb() trafgen performance considerably sank on hosts with many cores after the blamed commit. packet_read_pending() is very expensive, and calling it in af_packet fast path defeats Daniel intent in commit b013840810c2 ("packet: use percpu mmap tx frame pending refcount") tpacket_destruct_skb() makes room for one packet, we can immediately wakeup a producer, no need to completely drain the tx ring. Fixes: 89ed5b519004 ("af_packet: Block execution of tasks waiting for transmit to complete in AF_PACKET") Signed-off-by: Eric Dumazet Cc: Neil Horman Cc: Daniel Borkmann Reviewed-by: Willem de Bruijn Link: https://lore.kernel.org/r/20240515163358.4105915-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: CKI Backport Bot --- net/packet/af_packet.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 9994704c2706..561710c035ba 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2489,8 +2489,7 @@ static void tpacket_destruct_skb(struct sk_buff *skb) ts = __packet_set_timestamp(po, ph, skb); __packet_set_status(po, ph, TP_STATUS_AVAILABLE | ts); - if (!packet_read_pending(&po->tx_ring)) - complete(&po->skb_completion); + complete(&po->skb_completion); } sock_wfree(skb);