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From: Eric Dumazet <eric.dumazet@gmail.com>
To: Yafang Shao <laoar.shao@gmail.com>
Cc: David Miller <davem@davemloft.net>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	netdev@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH net-next] net: init sk_cookie for inet socket
Date: Tue, 24 Apr 2018 05:37:13 -0700	[thread overview]
Message-ID: <45bfd7ce-ecfa-8a4d-b1ed-8914a6b90093@gmail.com> (raw)
In-Reply-To: <CALOAHbDajHPN9Z3TTWFBwpd1H16RVRRYYiUMrUELE3JxeZo+qw@mail.gmail.com>



On 04/24/2018 04:47 AM, Yafang Shao wrote:

> 
> Could you pls. explain the issue to me ?

Just run a synflood test on your host, it will definitely show the atomic
consuming most cpu cycles in inet_reqsk_alloc(), because of huge contention
on a cache line shared by all cpus.

Performance is reduced from ~5 Mpps to ~3.8 Mpps with 16 RX queues on my host.

atomic64_inc_return(&sock_net(sk)->cookie_gen) was not meant to be used in the
normal case (when a socket cookie is not ever requested/needed)

      reply	other threads:[~2018-04-24 12:37 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-22 13:50 [PATCH net-next] net: init sk_cookie for inet socket Yafang Shao
2018-04-23 15:58 ` David Miller
2018-04-23 16:09   ` Eric Dumazet
2018-04-24  4:39     ` Yafang Shao
2018-04-24 11:41       ` Eric Dumazet
2018-04-24 11:47         ` Yafang Shao
2018-04-24 12:37           ` Eric Dumazet [this message]

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