From: David Miller <davem@davemloft.net>
To: mingo@elte.hu
Cc: dada1@cosmosbay.com, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl
Subject: Re: [RFC,PATCH] loopback: calls netif_receive_skb() instead of netif_rx()
Date: Mon, 31 Mar 2008 03:08:48 -0700 (PDT) [thread overview]
Message-ID: <20080331.030848.175668431.davem@davemloft.net> (raw)
In-Reply-To: <20080331094823.GA11651@elte.hu>
From: Ingo Molnar <mingo@elte.hu>
Date: Mon, 31 Mar 2008 11:48:23 +0200
>
> * Eric Dumazet <dada1@cosmosbay.com> wrote:
>
> > I noticed some paths in kernel are very stack aggressive, and on i386
> > with CONFIG_4KSTACKS we were really in a dangerous land, even without
> > my patch.
> >
> > What we call 4K stacks is in fact 4K - sizeof(struct task_struct), so
> > a litle bit more than 2K. [...]
>
> that's just wrong - 4K stacks on x86 are 4K-sizeof(thread_info) - the
> task struct is allocated elsewhere. The patch below runs just fine on
> 4K-stack x86.
I don't think it's safe.
Every packet you receive can result in a sent packet, which
in turn can result in a full packet receive path being
taken, and yet again another sent packet.
And so on and so forth.
Some cases like this would be stack bugs, but wouldn't
you like that bug to be a very busy cpu instead of a
crash from overrunning the current stack?
next prev parent reply other threads:[~2008-03-31 10:08 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-21 18:51 [RFC,PATCH] loopback: calls netif_receive_skb() instead of netif_rx() Eric Dumazet
2008-02-21 20:14 ` Daniel Lezcano
2008-02-21 23:19 ` Eric Dumazet
2008-02-22 10:19 ` Daniel Lezcano
2008-02-27 2:21 ` David Miller
2008-02-27 7:20 ` Jarek Poplawski
2008-02-27 7:23 ` David Miller
2008-02-27 7:34 ` Jarek Poplawski
2008-03-01 10:26 ` Eric Dumazet
2008-03-04 4:55 ` David Miller
2008-03-04 5:15 ` Stephen Hemminger
2008-03-04 6:27 ` Eric Dumazet
2008-03-23 10:29 ` David Miller
2008-03-23 18:48 ` Eric Dumazet
2008-03-23 19:15 ` Andi Kleen
2008-03-29 1:36 ` David Miller
2008-03-29 8:18 ` Eric Dumazet
2008-03-29 23:54 ` David Miller
2008-03-31 6:38 ` Eric Dumazet
2008-03-31 9:48 ` Ingo Molnar
2008-03-31 10:01 ` Eric Dumazet
2008-03-31 10:12 ` Ingo Molnar
2008-04-01 9:19 ` Eric Dumazet
2008-04-03 14:06 ` Pavel Machek
2008-04-03 16:19 ` Eric Dumazet
2008-03-31 10:08 ` David Miller [this message]
2008-03-31 10:44 ` Ingo Molnar
2008-03-31 11:02 ` David Miller
2008-03-31 11:36 ` poor network loopback performance and scalability (was: Re: [RFC,PATCH] loopback: calls netif_receive_skb() instead of netif_rx()) Ingo Molnar
2008-04-21 3:24 ` Herbert Xu
2008-04-21 3:38 ` poor network loopback performance and scalability David Miller
2008-04-21 8:11 ` Ingo Molnar
2008-04-21 8:16 ` David Miller
2008-04-21 10:19 ` Herbert Xu
2008-04-21 10:22 ` David Miller
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