linux-kernel - Re: 2.6.35-rc3: System unresponsive under load

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Message-ID: <AANLkTikAhqIz56xfUBBuQStMq9FqQp1sVZwhZ_Y4XAm5@mail.gmail.com>
Date:	Tue, 6 Jul 2010 18:01:45 +0200
From:	Luca Tettamanti <kronos.it@...il.com>
To:	Manfred Spraul <manfred@...orfullife.com>
Cc:	Christoph Lameter <cl@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Julia Lawall <julia@...u.dk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	maciej.rutecki@...il.com,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: 2.6.35-rc3: System unresponsive under load

On Wed, Jun 30, 2010 at 9:07 PM, Manfred Spraul
<manfred@...orfullife.com> wrote:
> Attached is a new idea, could you try it with your httpd test?

Will test ASAP.

> Perhaps the race is actually a race in the user space:
> The exit path of semtimedop() does not contain an explicit memory barrier.
> For the kernel, it does not matter: It merely reads one integer value.
> If sysret is also no memory barrier, then user space might observe stale
> data.
>
> Which cpu do you have? I was unable to show any misbehavior on a Phenom X4.

Intel(R) Core(TM)2 Duo CPU     T7500  @ 2.20GHz

I also have a Phenom X4, but I'm currently waiting a replacement for the PSU...

Luca
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