From: Paolo Bonzini <pbonzini@redhat.com>
To: Kevin Wolf <kwolf@redhat.com>
Cc: qemu-devel@nongnu.org, famz@redhat.com, stefanha@redhat.com,
qemu-block@nongnu.org, mreitz@redhat.com
Subject: Re: [Qemu-devel] [Qemu-block] [PATCH 07/19] block: Really pause block jobs on drain
Date: Fri, 13 Apr 2018 13:05:25 +0200 [thread overview]
Message-ID: <a8e995b9-039d-0f0c-25a1-eaa8ee1ea725@redhat.com> (raw)
In-Reply-To: <20180413080105.GA4134@localhost.localdomain>
On 13/04/2018 10:01, Kevin Wolf wrote:
>> Or bs->quiescent, for the sake of bikeshedding.
> Yes, that sounds better.
>
> The only problem with the proposal as I made it is that it's wrong. We
> can't keep bs->quiescent until bdrv_do_drained_end() because the caller
> can issue new requests and then have a nested drained section that needs
> to wait for all requests again instead of deciding that everything is
> already quiescent.
>
> Maybe where we should really reset it is in the initial recursion of
> bdrv_do_drained_begin(), specifically in bdrv_do_drained_begin_quiesce()
> which is called by both the parent and the child recursion.
>
> There don't seem to be completely obviously correct solutions (can't an
> I/O thread be draining a specific node while the main loop runs
> drain_all?), but this would probably be the most obvious one.
Or use a hash table?
Paolo
next prev parent reply other threads:[~2018-04-13 11:05 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-11 16:39 [Qemu-devel] [PATCH 00/19] Drain fixes and cleanups, part 3 Kevin Wolf
2018-04-11 16:39 ` [Qemu-devel] [PATCH 01/19] test-bdrv-drain: bdrv_drain() works with cross-AioContext events Kevin Wolf
2018-04-11 16:39 ` [Qemu-devel] [PATCH 02/19] block: Use bdrv_do_drain_begin/end in bdrv_drain_all() Kevin Wolf
2018-04-20 7:07 ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2018-04-11 16:39 ` [Qemu-devel] [PATCH 03/19] block: Remove 'recursive' parameter from bdrv_drain_invoke() Kevin Wolf
2018-04-20 7:09 ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2018-04-11 16:39 ` [Qemu-devel] [PATCH 04/19] block: Don't manually poll in bdrv_drain_all() Kevin Wolf
2018-04-11 18:32 ` Eric Blake
2018-04-20 7:11 ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2018-04-11 16:39 ` [Qemu-devel] [PATCH 05/19] tests/test-bdrv-drain: bdrv_drain_all() works in coroutines now Kevin Wolf
2018-04-11 18:33 ` Eric Blake
2018-04-20 7:12 ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2018-04-11 16:39 ` [Qemu-devel] [PATCH 06/19] block: Avoid unnecessary aio_poll() in AIO_WAIT_WHILE() Kevin Wolf
2018-04-11 17:33 ` Su Hang
2018-04-20 7:17 ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2018-04-11 16:39 ` [Qemu-devel] [PATCH 07/19] block: Really pause block jobs on drain Kevin Wolf
2018-04-12 8:37 ` Paolo Bonzini
2018-04-12 9:51 ` Kevin Wolf
2018-04-12 10:12 ` Paolo Bonzini
2018-04-12 11:11 ` Kevin Wolf
2018-04-12 11:30 ` Paolo Bonzini
2018-04-12 11:53 ` Kevin Wolf
2018-04-12 12:02 ` Paolo Bonzini
2018-04-12 13:27 ` Kevin Wolf
2018-04-12 13:42 ` Paolo Bonzini
2018-04-12 14:25 ` Kevin Wolf
2018-04-12 20:44 ` Paolo Bonzini
2018-04-13 8:01 ` Kevin Wolf
2018-04-13 11:05 ` Paolo Bonzini [this message]
2018-04-13 12:40 ` [Qemu-devel] [Qemu-block] " Kevin Wolf
2018-04-11 16:39 ` [Qemu-devel] [PATCH 08/19] block: Remove bdrv_drain_recurse() Kevin Wolf
2018-04-12 8:39 ` Paolo Bonzini
2018-04-20 7:20 ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2018-04-11 16:39 ` [Qemu-devel] [PATCH 09/19] test-bdrv-drain: Add test for node deletion Kevin Wolf
2018-04-20 7:32 ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2018-04-11 16:39 ` [Qemu-devel] [PATCH 10/19] block: Drain recursively with a single BDRV_POLL_WHILE() Kevin Wolf
2018-04-12 8:41 ` Paolo Bonzini
2018-04-11 16:39 ` [Qemu-devel] [PATCH 11/19] test-bdrv-drain: Test node deletion in subtree recursion Kevin Wolf
2018-04-11 16:39 ` [Qemu-devel] [PATCH 12/19] block: Don't poll in parent drain callbacks Kevin Wolf
2018-04-11 16:39 ` [Qemu-devel] [PATCH 13/19] test-bdrv-drain: Graph change through parent callback Kevin Wolf
2018-04-11 16:39 ` [Qemu-devel] [PATCH 14/19] block: Defer .bdrv_drain_begin callback to polling phase Kevin Wolf
2018-06-27 14:30 ` Max Reitz
2018-06-29 15:14 ` Kevin Wolf
2018-04-11 16:39 ` [Qemu-devel] [PATCH 15/19] test-bdrv-drain: Test that bdrv_drain_invoke() doesn't poll Kevin Wolf
2018-04-11 16:39 ` [Qemu-devel] [PATCH 16/19] block: Allow AIO_WAIT_WHILE with NULL ctx Kevin Wolf
2018-04-12 8:43 ` Paolo Bonzini
2018-04-11 16:39 ` [Qemu-devel] [PATCH 17/19] block: Move bdrv_drain_all_begin() out of coroutine context Kevin Wolf
2018-04-11 16:39 ` [Qemu-devel] [PATCH 18/19] block: Allow graph changes in bdrv_drain_all_begin/end sections Kevin Wolf
2018-04-12 8:47 ` Paolo Bonzini
2018-04-11 16:39 ` [Qemu-devel] [PATCH 19/19] test-bdrv-drain: Test graph changes in drain_all section Kevin Wolf
2018-04-11 17:05 ` [Qemu-devel] [PATCH 00/19] Drain fixes and cleanups, part 3 no-reply
2018-04-20 7:35 ` Stefan Hajnoczi
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