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From: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
To: Shaohua Li <shaohua.li-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Cc: kvm-devel
	<kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>,
	Andrew Morton
	<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
Subject: Re: [PATCH] KVM breaks CPU hotplug
Date: Mon, 26 Mar 2007 12:58:17 +0200	[thread overview]
Message-ID: <4607A749.30603@qumranet.com> (raw)
In-Reply-To: <46078E2C.9010100-atKUWr5tajBWk0Htik3J/w@public.gmane.org>

Avi Kivity wrote:
> Shaohua Li wrote:
>> When testing CPU hotplug, I found cpu can't be onlined with kvm enabled
>> sometimes. The reason is smp_call_function_single is a nop if the thread
>> is running on the target cpu. I think CPU_ONLINE case doesn't require
>> the fix as the online CPU isn't plugged into sheduler yet.
>>
>>   
>
> I think this is not enough, because:
>
> - this path is preemptible code, so the test (this_cpu == cpu) can run 
> one on cpu and execute later code on another
>> +        this_cpu = get_cpu();

...

>> +        put_cpu();

Sorry, I see you handled that.  But the other argument (scheduling vcpus 
later on same cpu) still holds, I think.

-- 
error compiling committee.c: too many arguments to function


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  parent reply	other threads:[~2007-03-26 10:58 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-03-26  8:48 [PATCH] KVM breaks CPU hotplug Shaohua Li
     [not found] ` <1174898893.14063.7.camel-yAZKuqJtXNMXR+D7ky4Foa2pdiUAq4bhAL8bYrjMMd8@public.gmane.org>
2007-03-26  9:11   ` Avi Kivity
     [not found]     ` <46078E2C.9010100-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-03-26 10:58       ` Avi Kivity [this message]
     [not found]         ` <4607A749.30603-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-03-27  1:12           ` Li, Shaohua
     [not found]             ` <FC1D1B23302A22499C60C967336B2AE00100CB7F-wq7ZOvIWXbNpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2007-03-27  6:38               ` Avi Kivity

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