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From: Cong Wang <xiyou.wangcong@gmail.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>,
	Linux Kernel Network Developers <netdev@vger.kernel.org>
Subject: Re: [net-next PATCH 1/3] Revert "icmp: avoid allocating large struct on stack"
Date: Mon, 9 Jan 2017 09:59:34 -0800	[thread overview]
Message-ID: <CAM_iQpV6YQ6nh_Y0f3BDgMheOic3bPiqQ1oNHR+saxxE7nBuoA@mail.gmail.com> (raw)
In-Reply-To: <1483984208.5846.9.camel@edumazet-glaptop3.roam.corp.google.com>

On Mon, Jan 9, 2017 at 9:50 AM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> On Mon, 2017-01-09 at 09:42 -0800, Cong Wang wrote:
>> On Mon, Jan 9, 2017 at 7:04 AM, Jesper Dangaard Brouer
>> <brouer@redhat.com> wrote:
>> > This reverts commit 9a99d4a50cb8 ("icmp: avoid allocating large struct
>> > on stack"), because struct icmp_bxm no really a large struct, and
>> > allocating and free of this small 112 bytes hurts performance.
>>
>> The original commit fixes a warning for large stack usage, icmp_send()
>> is deep in the call stack.
>>
>> Your optimization for a slow path makes no sense to me.
>
> Do you have the stack trace of this event ?
>
> Even Linus allowed vmalloc() kernel stacks, while it certainly was an
> heresy 10 years ago.
>
> I doubt it makes a difference trying to save 104 bytes of kernel stack.

I think you should have known this, quote from Eric Dumazet
(hopefully the same one):

    On Fri, 2013-05-31 at 22:22 -0700, Eric Dumazet wrote:

    Strange, I posted a patch like that some days ago.

which is from: https://patchwork.ozlabs.org/patch/248051/

Facepalm...

  reply	other threads:[~2017-01-09 17:59 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-01-09 15:03 [net-next PATCH 0/3] net: optimize ICMP-reply code path Jesper Dangaard Brouer
2017-01-09 15:04 ` [net-next PATCH 1/3] Revert "icmp: avoid allocating large struct on stack" Jesper Dangaard Brouer
2017-01-09 17:42   ` Cong Wang
2017-01-09 17:50     ` Eric Dumazet
2017-01-09 17:59       ` Cong Wang [this message]
2017-01-09 18:07         ` Eric Dumazet
2017-01-09 18:52           ` David Miller
2017-01-09 20:53             ` Jesper Dangaard Brouer
2017-01-10 18:06             ` Cong Wang
2017-01-10 18:12               ` David Miller
2017-01-10 18:44                 ` Cong Wang
2017-01-10 18:48                   ` Cong Wang
2017-01-10 18:54                   ` David Miller
2017-01-12 22:46                     ` Cong Wang
2017-01-10 20:08                   ` Jesper Dangaard Brouer
2017-01-10 21:48                     ` Eric Dumazet
2017-01-12 22:21                       ` Cong Wang
2017-01-10 21:41                 ` Joe Perches
2017-01-09 19:33           ` Joe Perches
2017-01-10 18:01           ` Cong Wang
2017-01-09 18:47         ` David Miller
2017-01-09 17:42   ` Eric Dumazet
2017-01-09 15:04 ` [net-next PATCH 2/3] net: reduce cycles spend on ICMP replies that gets rate limited Jesper Dangaard Brouer
2017-01-09 17:44   ` Eric Dumazet
2017-01-11 17:15     ` Eric Dumazet
2017-06-04  7:11   ` Florian Weimer
2017-06-04 14:38     ` Jesper Dangaard Brouer
2017-06-05 14:22       ` Florian Weimer
2017-01-09 15:04 ` [net-next PATCH 3/3] net: for rate-limited ICMP replies save one atomic operation Jesper Dangaard Brouer
2017-01-09 17:44   ` Eric Dumazet
2017-01-09 17:43 ` [net-next PATCH 0/3] net: optimize ICMP-reply code path Cong Wang
2017-01-09 17:56   ` Eric Dumazet
2017-01-09 20:49 ` David Miller

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