Re: [PATCH v2] core, x86: Add user return notifiers

Avi Kivity
2009-09-22T09:49:06Z

On 09/22/2009 12:37 PM, Arjan van de Ven wrote:
> On Tue, 22 Sep 2009 12:25:33 +0300
> Avi Kivity<avi@redhat.com> wrote:
>
>
>> On 09/19/2009 09:40 AM, Avi Kivity wrote:
>>
>>> Add a general per-cpu notifier that is called whenever the kernel is
>>> about to return to userspace. The notifier uses a thread_info flag
>>> and existing checks, so there is no impact on user return or context
>>> switch fast paths.
>>>
>>>
>> Ingo/Peter?
>>
> isn't this like really expensive when used ?
>

No, why? It triggers a call to do_notify_resume() and a walks a list of
length 1.

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error compiling committee.c: too many arguments to function