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Re: [Xen-devel] [PATCH][QEMU] Make active-timers thread-safe

To: "Daniel P. Berrange" <berrange@xxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH][QEMU] Make active-timers thread-safe
From: "Dave Lively" <dave.lively@xxxxxxxxx>
Date: Wed, 29 Aug 2007 15:36:55 -0400
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
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Hi Daniel -
  While I agree this patch wasn't necessary, I was curious why it was
even compiling for us (it was "auto-ported" to our unstable tree
without human intervention) since the patch introduces uses of pthread
data structures but doesn't introduce an include of <pthread.h>.  I
notice tools/ioemu/vl.h is still including <pthread.h> for i386/x86_64
to implement a mapcache lock.  Isn't this now unnecessary for the same


On 8/27/07, Daniel P. Berrange <berrange@xxxxxxxxxx> wrote:
> On Mon, Aug 27, 2007 at 02:58:26PM -0400, Ben Guthro wrote:
> > Protect active_timers[] lists with mutexes so timers can be safely used
> > from different threads.
> What code in QEMU is actually still using threads ? There used to be a Xen
> specific patch to the IDE layer to perform DMA ops in threads, but that was
> removed when xen-unstable synced with QEMU 0.9.0. Not aware of anything
> else using threads in the QEMU device model - its pretty dangerous because
> QEMU's internal data structures basically all assume single-threaded access.
> Regards,
> Dan.
> --
> |=- Red Hat, Engineering, Emerging Technologies, Boston.  +1 978 392 2496 -=|
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