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Date: Mon, 04 Jan 2010 17:54:13 -0600
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: [Qemu-devel] Re: [PATCH 11/19] use a bottom half to run timers
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>, qemu-devel@nongnu.org

On 01/04/2010 02:01 PM, Michael S. Tsirkin wrote:
> On Mon, Jan 04, 2010 at 02:24:53PM -0600, Anthony Liguori wrote:
>    
>> On 12/21/2009 02:09 AM, Paolo Bonzini wrote:
>>      
>>> Make the timer subsystem register its own bottom half instead of
>>> placing the bottom half code in the heart of the main loop.  To
>>> test if an alarm timer is pending, just check if the bottom half is
>>> scheduled.
>>>
>>> Signed-off-by: Paolo Bonzini<pbonzini@redhat.com>
>>>        
>> I'm not a huge fan of this for a couple reasons.  The first is that it
>> introduces a subtle semantic change.  Previously, timers always ran
>> before bottom halves whereas after this change, timers may run after
>> some bottoms halves but before others.  While this should be okay in
>> principle, in practice, I'm sure it'll introduce regressions.  I'd be
>> very surprised if cris wasn't affected by this.
>>
>> But more importantly, I think timer dispatch needs to be part of the
>> select loop.  malc has a git tree that replaces host alarm timers with
>> select() timeouts.
>>      
> Where is that tree?
>    

http://repo.or.cz/w/qemu/malc.git  mtloop

> IMO we need that, I am not sure all code is as signal-safe
> as it should be. At least crashes that I saw with winxp install
> seem to be related to signal handling.
>    

Regards,

Anthony Liguori