Re: [Qemu-devel] "iothread: release iothread around aio_poll" causes random hangs at startup

[Christian Borntraeger <borntraeger@de.ibm.com>]

Am 16.07.2015 um 13:20 schrieb Paolo Bonzini:
> 
> 
> On 16/07/2015 13:03, Christian Borntraeger wrote:
>> For what its worth, I can no longer reproduce the issue on
>> current master + cherry-pick of a0710f7995f (iothread: release iothread around aio_poll)
>>
>> bisect tells me that
>>
>> commit 53ec73e264f481b79b52efcadc9ceb8f8996975c
>> Author:     Fam Zheng <famz@redhat.com>
>> AuthorDate: Fri May 29 18:53:14 2015 +0800
>> Commit:     Stefan Hajnoczi <stefanha@redhat.com>
>> CommitDate: Tue Jul 7 14:27:14 2015 +0100
>>
>>     block: Use bdrv_drain to replace uncessary bdrv_drain_all
>>
>> made the problem will blk-null go away. I still dont understand why.
> 
> It could be related to the AioContext problem that I'm fixing these
> days, too.  Good news, we'll requeue the patch for 2.5.

That was also something that I had in mind (in fact I retested this to check
the ctx patch). master + cherry-pick of a0710f7995f + revert of 53ec73e26 + this fix
still fails, so it was (is?) a different issue. The interesting part is that this
problem required 2 or more disk (and we replace drain_all with single drains) so
it somewhat sounds plausible.

Christian