From: Eric Dumazet <edumazet@google.com>
Date: Thu, 6 Nov 2025 08:55:00 +0000 (+0000)
Subject: net: add prefetch() in skb_defer_free_flush()
X-Git-Tag: v6.19-rc1~170^2~206
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=fd9557c3606bb683c01a6c7627e915b539b9a8df;p=thirdparty%2Flinux.git

net: add prefetch() in skb_defer_free_flush()

skb_defer_free_flush() is becoming more important these days.

Add a prefetch operation to reduce latency a bit on some
platforms like AMD EPYC 7B12.

On more recent cpus, a stall happens when reading skb_shinfo().
Avoiding it will require a more elaborate strategy.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Link: https://patch.msgid.link/20251106085500.2438951-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---

diff --git a/net/core/dev.c b/net/core/dev.c
index 537aa43edff0e..69515edd17bc6 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6782,6 +6782,7 @@ static void skb_defer_free_flush(void)
 		free_list = llist_del_all(&sdn->defer_list);
 
 		llist_for_each_entry_safe(skb, next, free_list, ll_node) {
+			prefetch(next);
 			napi_consume_skb(skb, 1);
 		}
 	}