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Date: Wed, 17 Jul 2013 17:09:58 +0100
From: Alex Bligh <alex@alex.org.uk>
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Subject: Re: [Qemu-devel] [PATCH] [RFC] aio/async: Add timed bottom-halves
Reply-To: Alex Bligh <alex@alex.org.uk>
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Anthony Liguori <aliguori@us.ibm.com>, Alex Bligh <alex@alex.org.uk>, Stefan Hajnoczi <stefanha@gmail.com>, qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>, rth@twiddle.net

Paolo,

--On 17 July 2013 10:11:07 +0200 Paolo Bonzini <pbonzini@redhat.com> wrote:

>>> The steps to achieving this:
>>>
>>> 1. Drop alarm timers from qemu-timer.c and calculate g_poll() timeout
>>>    instead for the main loop.
>>>
>>> 2. Introduce a per-AioContext aio_ctx_clock that can be used with
>>>    qemu_new_timer() to create a QEMUTimer that expires during
>>>    aio_poll().
>>>
>>> 3. Calculate g_poll() timeout for aio_ctx_clock in aio_poll().
>>
>> A couple of questions:
>>
>> 1. How would this work where the user has no main loop, e.g. qemu-img? A
>>   block driver may well still need timers.
>
> The block driver should only use aio_ctx_clock, and those _would_ be
> handled in aio_poll().

OK, so modify aio_poll not to run qemu_run_all_timers but to run
qemu_run_timer on that particular clock.

We'd still need to modify some of the executables to call init_timers()
or whatever it is, but that's easy enough.

I might have a go at that.

-- 
Alex Bligh