From: Fam Zheng <famz@redhat.com>
To: Kevin Wolf <kwolf@redhat.com>
Cc: qemu-block@nongnu.org, qemu-devel@nongnu.org,
Max Reitz <mreitz@redhat.com>,
Ed Swierk <eswierk@skyportsystems.com>,
Stefan Hajnoczi <stefanha@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [Qemu-devel] [PATCH for 2.9 v3 09/10] block: Use bdrv_coroutine_enter to start I/O coroutines
Date: Tue, 11 Apr 2017 19:37:45 +0800 [thread overview]
Message-ID: <20170411113745.GB8507@lemon> (raw)
In-Reply-To: <20170411100642.GH4516@noname.str.redhat.com>
On Tue, 04/11 12:06, Kevin Wolf wrote:
> > tests/qemu-iotests/109.out | 10 +++++-----
>
> This one is curious. Why do we copy more data depending on how the job
> coroutine is reentered?
I did trace it and think the difference is not very important: on master, the
second iteration of the mirror_run loop gets a chance to run, and there we have:
s->common.len = s->common.offset +
(cnt + s->sectors_in_flight) * BDRV_SECTOR_SIZE;
E.g. in the mirror job of the first updated output, iter #1 has cnt = 128
and s->sectors_in_flight = 0; iter #2 has cnt = 0, s->sectors_in_flight = 2.
I think the reason is simply that co_queue_wakeup in bdrv_coroutine_enter subtly
changed how the mirror coroutine and bdrv_co_pwritev are ordered.
Fam
next prev parent reply other threads:[~2017-04-11 11:37 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-10 15:05 [Qemu-devel] [PATCH for 2.9 v3 00/10] block: Fixes regarding dataplane and management operations Fam Zheng
2017-04-10 15:05 ` [Qemu-devel] [PATCH for 2.9 v3 01/10] block: Make bdrv_parent_drained_begin/end public Fam Zheng
2017-04-11 9:02 ` Kevin Wolf
2017-04-11 10:30 ` Stefan Hajnoczi
2017-04-10 15:05 ` [Qemu-devel] [PATCH for 2.9 v3 02/10] block: Quiesce old aio context during bdrv_set_aio_context Fam Zheng
2017-04-11 9:02 ` Kevin Wolf
2017-04-11 10:30 ` Stefan Hajnoczi
2017-04-10 15:05 ` [Qemu-devel] [PATCH for 2.9 v3 03/10] tests/block-job-txn: Don't start block job before adding to txn Fam Zheng
2017-04-11 9:04 ` Kevin Wolf
2017-04-10 15:05 ` [Qemu-devel] [PATCH for 2.9 v3 04/10] coroutine: Extract qemu_aio_coroutine_enter Fam Zheng
2017-04-10 15:05 ` [Qemu-devel] [PATCH for 2.9 v3 05/10] async: Introduce aio_co_enter and aio_co_enter_if_inactive Fam Zheng
2017-04-11 9:28 ` Kevin Wolf
2017-04-11 11:07 ` Fam Zheng
2017-04-10 15:05 ` [Qemu-devel] [PATCH for 2.9 v3 06/10] block: Introduce bdrv_coroutine_enter and *_if_inactive Fam Zheng
2017-04-10 15:05 ` [Qemu-devel] [PATCH for 2.9 v3 07/10] blockjob: Use bdrv_coroutine_enter to start coroutine Fam Zheng
2017-04-10 15:05 ` [Qemu-devel] [PATCH for 2.9 v3 08/10] qemu-io-cmds: Use bdrv_coroutine_enter Fam Zheng
2017-04-10 15:05 ` [Qemu-devel] [PATCH for 2.9 v3 09/10] block: Use bdrv_coroutine_enter to start I/O coroutines Fam Zheng
2017-04-10 15:38 ` Eric Blake
2017-04-11 10:06 ` Kevin Wolf
2017-04-11 11:37 ` Fam Zheng [this message]
2017-04-11 11:43 ` Paolo Bonzini
2017-04-10 15:05 ` [Qemu-devel] [PATCH for 2.9 v3 10/10] block: Fix bdrv_co_flush early return Fam Zheng
2017-04-11 9:19 ` Paolo Bonzini
2017-04-25 15:16 ` Kevin Wolf
2017-04-26 0:39 ` Fam Zheng
2017-04-11 10:52 ` [Qemu-devel] [PATCH for 2.9 v3 00/10] block: Fixes regarding dataplane and management operations Stefan Hajnoczi
2017-04-11 11:05 ` Kevin Wolf
2017-04-11 11:55 ` Fam Zheng
2017-04-11 11:13 ` [Qemu-devel] [PATCH for 2.9 v3 11/10] block, async: Remove unused *_enter_if_inactive() Kevin Wolf
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