From: Max Reitz <mreitz@redhat.com>
To: Qemu-block <qemu-block@nongnu.org>
Cc: Alberto Garcia <berto@igalia.com>,
Anton Nefedov <anton.nefedov@virtuozzo.com>,
Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Subject: Re: Problems with c8bb23cbdbe3 on ppc64le
Date: Mon, 21 Oct 2019 18:24:00 +0200 [thread overview]
Message-ID: <2bf96cbd-0836-bd48-a2fc-84f5a630939d@redhat.com> (raw)
In-Reply-To: <120ab7dc-17dd-2796-95a3-8492ca40339e@redhat.com>
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On 21.10.19 15:33, Max Reitz wrote:
> On 10.10.19 17:17, Max Reitz wrote:
>> Hi everyone,
>>
>> (CCs just based on tags in the commit in question)
>>
>> I have two bug reports which claim problems of qcow2 on XFS on ppc64le
>> machines since qemu 4.1.0. One of those is about bad performance
>> (sorry, is isn’t public :-/), the other about data corruption
>> (https://bugzilla.redhat.com/show_bug.cgi?id=1751934).
>>
>> It looks like in both cases reverting c8bb23cbdbe3 solves the problem
>> (which optimized COW of unallocated areas).
>>
>> I think I’ve looked at every angle but can‘t find what could be wrong
>> with it. Do any of you have any idea? :-/
>
> I now have a reproducer with CentOS, so it’s actually useful outside of
> Red Hat:
I’ve run this test with various configurations, and the installation
does not fail on tmpfs, ext4, btrfs; or without cache.direct=on,aio=native.
(So the installation only fails on xfs and aio=native. I’ve tried both
virtio-scsi and virtio-blk, but it fails with both. I did test a
loop-mounted xfs volume, and the installation fails there, too,
regardless of whether the raw xfs image is placed on ext4 or tmpfs.[1])
Unfortunately I still don’t have a more concise reproducer that would
clearly show that this is a kernel bug. So for the time being I still
don’t know what causes it.
Max
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next prev parent reply other threads:[~2019-10-21 16:25 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-10 15:17 Problems with c8bb23cbdbe3 on ppc64le Max Reitz
2019-10-10 16:15 ` Anton Nefedov
2019-10-11 7:49 ` Max Reitz
2019-10-21 11:40 ` Max Reitz
2019-10-21 13:33 ` Max Reitz
2019-10-21 16:24 ` Max Reitz [this message]
2019-10-24 9:08 ` Max Reitz
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