From: Jakub Kicinski <kuba@kernel.org>
To: Eric Dumazet <edumazet@google.com>
Cc: "David S . Miller" <davem@davemloft.net>,
Paolo Abeni <pabeni@redhat.com>, Simon Horman <horms@kernel.org>,
netdev@vger.kernel.org, eric.dumazet@gmail.com
Subject: Re: [PATCH net-next] net: split kmalloc_reserve()
Date: Thu, 15 Jan 2026 20:06:53 -0800 [thread overview]
Message-ID: <20260115200653.6afa6149@kernel.org> (raw)
In-Reply-To: <20260114212840.2511487-1-edumazet@google.com>
On Wed, 14 Jan 2026 21:28:40 +0000 Eric Dumazet wrote:
> kmalloc_reserve() is too big to be inlined.
>
> Put the slow path in a new out-of-line function : kmalloc_pfmemalloc()
>
> Then let kmalloc_reserve() set skb->pfmemalloc only when/if
> the slow path is taken.
>
> This means __alloc_skb() is faster :
>
> - kmalloc_reserve() is now automatically inlined by both gcc and clang.
> - No more expensive RMW (skb->pfmemalloc = pfmemalloc).
> - No more expensive stack canary (for CONFIG_STACKPROTECTOR_STRONG=y).
> - Removal of two prefetches that were coming too late for modern cpus.
>
> Text size increase is quite small compared to the cpu savings (~0.5 %)
Could you resend? Looks like this depends on some of the patches that
were pending so it didn't apply when posted.
--
pw-bot: cr
next prev parent reply other threads:[~2026-01-16 4:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-14 21:28 [PATCH net-next] net: split kmalloc_reserve() Eric Dumazet
2026-01-16 4:06 ` Jakub Kicinski [this message]
2026-01-16 4:10 ` Eric Dumazet
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