From: "Denis V. Lunev" <den@openvz.org>
To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Kevin Wolf <kwolf@redhat.com>,
Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
qemu-devel@nongnu.org, qemu-block@nongnu.org,
Max Reitz <mreitz@redhat.com>
Subject: Re: [PATCH 0/2] block: add logging facility for long standing IO requests
Date: Fri, 31 Jul 2020 13:31:51 +0300 [thread overview]
Message-ID: <43df6148-cec5-a866-4b81-7f4020c70f7d@openvz.org> (raw)
In-Reply-To: <20200731102531.GC177875@stefanha-x1.localdomain>
On 7/31/20 1:25 PM, Stefan Hajnoczi wrote:
> On Fri, Jul 10, 2020 at 08:27:09PM +0300, Denis V. Lunev wrote:
>> There are severe delays with IO requests processing if QEMU is running in
>> virtual machine or over software defined storage. Such delays potentially
>> results in unpredictable guest behavior. For example, guests over IDE or
>> SATA drive could remount filesystem read-only if write is performed
>> longer than 10 seconds.
>>
>> Such reports are very complex to process. Some good starting point for this
>> seems quite reasonable. This patch provides one. It adds logging of such
>> potentially dangerous long IO operations.
>>
>> Signed-off-by: Denis V. Lunev <den@openvz.org>
>> CC: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>> CC: Kevin Wolf <kwolf@redhat.com>
>> CC: Max Reitz <mreitz@redhat.com>
> If I understand correctly this only reports completed I/Os, so if the
> host hasn't given up on an I/O request yet then QEMU will not report it
> is taking a long time. In the meantime the guest could start printing
> timeout errors.
>
> I think this patch series is good as it is. In the future maybe a QMP
> command that lists in-flight I/O requests would be nice. That helps
> when troubleshooting I/Os that are hung.
We could dump requests at block level, we do have proper lists,
but the would be a little bit different.
Anyway, I __DO__ like this idea, I have missed this somehow :)
Thank you for the suggestion,
Den
prev parent reply other threads:[~2020-07-31 10:33 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-10 17:27 [PATCH 0/2] block: add logging facility for long standing IO requests Denis V. Lunev
2020-07-10 17:27 ` [PATCH 1/2] block/block-backend: add converter from BlockAcctStats to BlockBackend Denis V. Lunev
2020-07-11 10:05 ` Vladimir Sementsov-Ogievskiy
2020-07-10 17:27 ` [PATCH 2/2] block: add logging facility for long standing IO requests Denis V. Lunev
2020-07-11 10:31 ` Vladimir Sementsov-Ogievskiy
2020-07-29 10:30 ` Stefan Hajnoczi
2020-07-29 11:06 ` Denis V. Lunev
2020-07-31 10:23 ` Stefan Hajnoczi
2020-07-29 10:31 ` [PATCH 0/2] " Stefan Hajnoczi
2020-07-31 10:25 ` Stefan Hajnoczi
2020-07-31 10:31 ` Denis V. Lunev [this message]
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