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From: Alexander Yarygin <yarygin@linux.vnet.ibm.com>
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	<20150616083905.GA22299@stefanha-thinkpad.redhat.com>
Date: Tue, 16 Jun 2015 12:08:58 +0300
In-Reply-To: <20150616083905.GA22299@stefanha-thinkpad.redhat.com> (Stefan
	Hajnoczi's message of "Tue, 16 Jun 2015 09:39:05 +0100")
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Subject: Re: [Qemu-devel] [PATCH 3/3] block: Let bdrv_drain_all() to call
	aio_poll() for each AioContext
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To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, qemu-block@nongnu.org, Ekaterina Tumanova <tumanova@linux.vnet.ibm.com>, qemu-devel@nongnu.org, Christian Borntraeger <borntraeger@de.ibm.com>, Cornelia Huck <cornelia.huck@de.ibm.com>, Paolo Bonzini <pbonzini@redhat.com>

Stefan Hajnoczi <stefanha@redhat.com> writes:

> On Wed, Jun 10, 2015 at 02:38:17PM +0300, Alexander Yarygin wrote:
>> After the commit 9b536adc ("block: acquire AioContext in
>> bdrv_drain_all()") the aio_poll() function got called for every
>> BlockDriverState, in assumption that every device may have its own
>> AioContext. If we have thousands of disks attached, there are a lot of
>> BlockDriverStates but only a few AioContexts, leading to tons of
>> unnecessary aio_poll() calls.
>> 
>> This patch changes the bdrv_drain_all() function allowing it find shared
>> AioContexts and to call aio_poll() only for unique ones.
>> 
>> Cc: Christian Borntraeger <borntraeger@de.ibm.com>
>> Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
>> Cc: Kevin Wolf <kwolf@redhat.com>
>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>> Cc: Stefan Hajnoczi <stefanha@redhat.com>
>> Signed-off-by: Alexander Yarygin <yarygin@linux.vnet.ibm.com>
>> ---
>>  block/io.c | 42 ++++++++++++++++++++++++++----------------
>>  1 file changed, 26 insertions(+), 16 deletions(-)
>
> Thanks, applied this patch only to my block tree:
> https://github.com/stefanha/qemu/commits/block
>
> Patch 2 has a pending issue and Patch 1 is only needed by Patch 2.
>
> Stefan

Ok, I will respin patches 1-2.
Thanks!