linux-kernel - Re: [PATCH] x86_64: fix delayed signals

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Date:	Fri, 11 Jul 2008 14:13:41 +0300
From:	Török Edwin <edwintorok@...il.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Roland McGrath <roland@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Elias Oltmanns <eo@...ensachen.de>,
	Arjan van de Ven <arjan@...radead.org>
Subject: Re: [PATCH] x86_64: fix delayed signals

On 2008-07-11 08:46, Ingo Molnar wrote:
> * Roland McGrath <roland@...hat.com> wrote:
>
>   
>> On three of the several paths in entry_64.S that call 
>> do_notify_resume() on the way back to user mode, we fail to properly 
>> check again for newly-arrived work that requires another call to 
>> do_notify_resume() before going to user mode.  These paths set the 
>> mask to check only _TIF_NEED_RESCHED, but this is wrong.  The other 
>> paths that lead to do_notify_resume() do this correctly already, and 
>> entry_32.S does it correctly in all cases.
>>     
>
> nice find! Roland, is this related to the thread started by Elias 
> Oltmanns yesterday:
>
>     http://lkml.org/lkml/2008/7/10/57
>   

I will try to get a latency trace using the debug features in
linux-next, but first
I have to bisect a boot failure in linux-next.

> which is also related to the thread started by Edwin Török:
>
>     http://lkml.org/lkml/2008/6/28/50
>
> ? The weight of complains seems to be on the 64-bit side, in those 
> threads 32-bit systems seem to be implicated as well by latencytop. 
> Perhaps the 64-bit delays are related to the bug you fix and we could 
> chalk up the 32-bit delays to IO delays?
>
> more people Cc:-ed: if your delays happen on 64-bit x86 systems - does 
> Roland's patch (also repeated below) fix those delay issues?
>
>   

Thanks for CC-ing me.
I will give the patch a try.

Best regards,
--Edwin

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