From: Eric Dumazet <edumazet@google.com>
Date: Fri, 21 Nov 2025 08:32:52 +0000 (+0000)
Subject: net: prefech skb->priority in __dev_xmit_skb()
X-Git-Tag: v6.19-rc1~170^2~83^2~4
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b2e9821cff6c3c9ac107fce5327070f4462bf8a7;p=thirdparty%2Fkernel%2Flinux.git

net: prefech skb->priority in __dev_xmit_skb()

Most qdiscs need to read skb->priority at enqueue time().

In commit 100dfa74cad9 ("net: dev_queue_xmit() llist adoption")
I added a prefetch(next), lets add another one for the second
half of skb.

Note that skb->priority and skb->hash share a common cache line,
so this patch helps qdiscs needing both fields.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20251121083256.674562-11-edumazet@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---

diff --git a/net/core/dev.c b/net/core/dev.c
index e19eb4e9d77c2..53e2496dc4292 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4246,6 +4246,7 @@ no_lock_out:
 
 		llist_for_each_entry_safe(skb, next, ll_list, ll_node) {
 			prefetch(next);
+			prefetch(&next->priority);
 			skb_mark_not_on_list(skb);
 			rc = dev_qdisc_enqueue(skb, q, &to_free, txq);
 			count++;