netdev - Re: [PATCH net-next v4 1/2] net: cache for same cpu skb_attempt_defer

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Message-ID: <CANn89iJf8JCpKM4kLx=mW5Hs3nyEKoK+ranqvTxjgE61YqtBPw@mail.gmail.com>
Date: Wed, 10 Apr 2024 20:47:19 +0200
From: Eric Dumazet <edumazet@...gle.com>
To: Pavel Begunkov <asml.silence@...il.com>
Cc: netdev@...r.kernel.org, davem@...emloft.net, dsahern@...nel.org, 
	pabeni@...hat.com, kuba@...nel.org
Subject: Re: [PATCH net-next v4 1/2] net: cache for same cpu skb_attempt_defer_free

On Wed, Apr 10, 2024 at 3:28 AM Pavel Begunkov <asml.silence@...il.com> wrote:
>
> Optimise skb_attempt_defer_free() when run by the same CPU the skb was
> allocated on. Instead of __kfree_skb() -> kmem_cache_free() we can
> disable softirqs and put the buffer into cpu local caches.
>
> CPU bound TCP ping pong style benchmarking (i.e. netbench) showed a 1%
> throughput increase (392.2 -> 396.4 Krps). Cross checking with profiles,
> the total CPU share of skb_attempt_defer_free() dropped by 0.6%. Note,
> I'd expect the win doubled with rx only benchmarks, as the optimisation
> is for the receive path, but the test spends >55% of CPU doing writes.
>
> Signed-off-by: Pavel Begunkov <asml.silence@...il.com>

Reviewed-by: Eric Dumazet <edumazet@...gle.com>