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From: Max Reitz <mreitz@redhat.com>
To: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
	qemu-block@nongnu.org
Cc: kwolf@redhat.com, wencongyang2@huawei.com,
	xiechanglong.d@gmail.com, qemu-devel@nongnu.org,
	armbru@redhat.com, den@openvz.org, jsnow@redhat.com
Subject: Re: [PATCH v4 00/23] backup performance: block_status + async
Date: Mon, 18 Jan 2021 16:07:58 +0100
Message-ID: <3d6f7b5a-49b6-bed8-8048-38552fa6292a@redhat.com> (raw)
In-Reply-To: <20210116214705.822267-1-vsementsov@virtuozzo.com>

On 16.01.21 22:46, Vladimir Sementsov-Ogievskiy wrote:
> Hi Max!
> I applied my series onto yours 129-fixing and found, that 129 fails for backup.
> And setting small max-chunk and even max-workers to 1 doesn't help! (setting
> speed like in v3 still helps).
> 
> And I found, that the problem is that really, the whole backup job goes during
> drain, because in new architecture we do just job_yield() during the whole
> background block-copy.

OK, so as it was in v3, the job was drained, but since it was already 
yielding while block-copy was running in the background, nothing 
happened; the block-copy completed and only then was the job woken (and 
then there was no reason to pause, because it was done already).

So now the job is entered on drain, too (not only user pauses), which 
means that it gets a chance to pause background requests.

In backup’s case, that means invoking job_yield() again, which sets a 
job_pause_point(), which will cancel the block-copy.  Once the job is 
unpaused (re-entered by job_resume()), backup sees block-copy is 
cancelled (and finished), leaves the loop, and retries with a new 
block-copy call.

I think I got it now.


So all that’s left is issuing a thanks to you – thanks! – and announcing 
that I’ve applied this series to my block branch (with s/not 
unsupported/not supported/ in patch 23):

https://git.xanclic.moe/XanClic/qemu/commits/branch/block

Max



  parent reply index

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-16 21:46 Vladimir Sementsov-Ogievskiy
2021-01-16 21:46 ` [PATCH v4 01/23] qapi: backup: add perf.use-copy-range parameter Vladimir Sementsov-Ogievskiy
2021-01-16 21:46 ` [PATCH v4 02/23] block/block-copy: More explicit call_state Vladimir Sementsov-Ogievskiy
2021-01-16 21:46 ` [PATCH v4 03/23] block/block-copy: implement block_copy_async Vladimir Sementsov-Ogievskiy
2021-01-16 21:46 ` [PATCH v4 04/23] block/block-copy: add max_chunk and max_workers parameters Vladimir Sementsov-Ogievskiy
2021-01-16 21:46 ` [PATCH v4 05/23] block/block-copy: add list of all call-states Vladimir Sementsov-Ogievskiy
2021-01-16 21:46 ` [PATCH v4 06/23] block/block-copy: add ratelimit to block-copy Vladimir Sementsov-Ogievskiy
2021-01-16 21:46 ` [PATCH v4 07/23] block/block-copy: add block_copy_cancel Vladimir Sementsov-Ogievskiy
2021-01-16 21:46 ` [PATCH v4 08/23] blockjob: add set_speed to BlockJobDriver Vladimir Sementsov-Ogievskiy
2021-01-16 21:46 ` [PATCH v4 09/23] job: call job_enter from job_pause Vladimir Sementsov-Ogievskiy
2021-01-18 13:45   ` Max Reitz
2021-01-18 14:20     ` Max Reitz
2021-04-07 11:19   ` Max Reitz
2021-04-07 11:38     ` Vladimir Sementsov-Ogievskiy
2021-04-21  8:31       ` Vladimir Sementsov-Ogievskiy
2021-01-16 21:46 ` [PATCH v4 10/23] qapi: backup: add max-chunk and max-workers to x-perf struct Vladimir Sementsov-Ogievskiy
2021-01-16 21:46 ` [PATCH v4 11/23] iotests: 56: prepare for backup over block-copy Vladimir Sementsov-Ogievskiy
2021-01-16 21:46 ` [PATCH v4 12/23] iotests: 185: " Vladimir Sementsov-Ogievskiy
2021-01-16 21:46 ` [PATCH v4 13/23] iotests: 219: " Vladimir Sementsov-Ogievskiy
2021-01-16 21:46 ` [PATCH v4 14/23] iotests: 257: " Vladimir Sementsov-Ogievskiy
2021-01-16 21:46 ` [PATCH v4 15/23] block/block-copy: make progress_bytes_callback optional Vladimir Sementsov-Ogievskiy
2021-01-16 21:46 ` [PATCH v4 16/23] block/backup: drop extra gotos from backup_run() Vladimir Sementsov-Ogievskiy
2021-01-16 21:46 ` [PATCH v4 17/23] backup: move to block-copy Vladimir Sementsov-Ogievskiy
2021-01-16 21:47 ` [PATCH v4 18/23] qapi: backup: disable copy_range by default Vladimir Sementsov-Ogievskiy
2021-01-16 21:47 ` [PATCH v4 19/23] block/block-copy: drop unused block_copy_set_progress_callback() Vladimir Sementsov-Ogievskiy
2021-01-16 21:47 ` [PATCH v4 20/23] block/block-copy: drop unused argument of block_copy() Vladimir Sementsov-Ogievskiy
2021-01-16 21:47 ` [PATCH v4 21/23] simplebench/bench_block_job: use correct shebang line with python3 Vladimir Sementsov-Ogievskiy
2021-01-16 21:47 ` [PATCH v4 22/23] simplebench: bench_block_job: add cmd_options argument Vladimir Sementsov-Ogievskiy
2021-01-16 21:47 ` [PATCH v4 23/23] simplebench: add bench-backup.py Vladimir Sementsov-Ogievskiy
2021-01-18 14:01   ` Max Reitz
2021-01-18 15:07 ` Max Reitz [this message]
2021-01-18 17:04   ` [PATCH v4 00/23] backup performance: block_status + async Vladimir Sementsov-Ogievskiy
2021-01-19 18:40 ` Max Reitz
2021-01-19 19:22   ` Vladimir Sementsov-Ogievskiy
2021-01-19 19:29     ` Vladimir Sementsov-Ogievskiy
2021-01-20 10:39     ` Max Reitz
2021-01-20 13:50       ` Max Reitz
2021-01-20 14:34         ` Max Reitz
2021-01-20 14:44           ` Max Reitz
2021-01-20 15:53             ` Max Reitz
2021-01-20 16:00               ` Max Reitz
2021-01-20 16:04               ` Daniel P. Berrangé
2021-01-20 16:40                 ` Max Reitz
2021-01-20 10:20 ` [PATCH v4 11.5/23] iotests/129: Limit backup's max-chunk/max-workers Max Reitz
2021-01-20 11:24   ` Vladimir Sementsov-Ogievskiy

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