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Re: [Qemu-devel] [patch 1/2] qemu: sem/thread helpers
From: |
Paul Brook |
Subject: |
Re: [Qemu-devel] [patch 1/2] qemu: sem/thread helpers |
Date: |
Tue, 17 Mar 2009 23:07:07 +0000 |
User-agent: |
KMail/1.9.9 |
On Tuesday 17 March 2009, Marcelo Tosatti wrote:
> On Sun, Mar 15, 2009 at 04:15:52PM +0200, Avi Kivity wrote:
> > Marcelo Tosatti wrote:
> >> +
> >> +struct QemuSem {
> >> + sem_t sema;
> >> +};
> >
> > Why aren't you using pthread_mutex_t?
>
> Because we want the thread waiting on the lock to be awakened
> once the holder releases it. This does not happen with pthread
> mutexes AFAIK.
Really? I'd be surprised if there's any difference. The whole point of a mutex
is that it blocks until the other thread releases it. At best it sounds like
you're making fairly sketchy assumptions about the host OS scheduler
heuristics.
Paul
[Qemu-devel] [patch 2/2] qemu: separate thread for io, Marcelo Tosatti, 2009/03/11