From: Eric Dumazet <edumazet@google.com>
To: "David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Paolo Abeni <pabeni@redhat.com>
Cc: netdev@vger.kernel.org, eric.dumazet@gmail.com,
Eric Dumazet <edumazet@google.com>,
Neil Horman <nhorman@tuxdriver.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Subject: [PATCH net] af_packet: do not call packet_read_pending() from tpacket_destruct_skb()
Date: Wed, 15 May 2024 16:33:58 +0000 [thread overview]
Message-ID: <20240515163358.4105915-1-edumazet@google.com> (raw)
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 <edumazet@google.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
---
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 8c6d3fbb4ed87f17c2e365810106a05fe9b8ff0c..ea3ebc160e25cc661901717a755f47db927c304d 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2522,8 +2522,7 @@ 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);
--
2.45.0.rc1.225.g2a3ae87e7f-goog
next reply other threads:[~2024-05-15 16:34 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-15 16:33 Eric Dumazet [this message]
2024-05-15 18:02 ` [PATCH net] af_packet: do not call packet_read_pending() from tpacket_destruct_skb() Willem de Bruijn
2024-05-17 2:40 ` patchwork-bot+netdevbpf
2024-05-21 9:34 ` Daniel Borkmann
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