From: Paolo Bonzini <pbonzini@redhat.com>
To: Kevin Wolf <kwolf@redhat.com>
Cc: ming.lei@canonical.com, pl@kamp.de, qemu-devel@nongnu.org,
stefanha@redhat.com
Subject: Re: [Qemu-devel] [PATCH 5/7] coroutine: rewrite pool to avoid mutex
Date: Fri, 28 Nov 2014 20:57:51 +0100 [thread overview]
Message-ID: <5478D3BF.1010405@redhat.com> (raw)
In-Reply-To: <20141128183401.GI4035@noname.redhat.com>
On 28/11/2014 19:34, Kevin Wolf wrote:
>>> > > Not sure if speculations about the future belong into commit messages,
>>> > > but while it may turn out that a bypass is required in the end (I hope
>>> > > it doesn't), the part about AIOCBs is wrong if you really consistently
>>> > > use coroutines all the way down from the device to the block driver.
>> >
>> > This is much harder for virtio-scsi than for virtio-blk, though.
> Why is that? At least replacing the bdrv_aio_*() call by
> coroutine_create/coroutine_enter/bdrv_co_*() is a mechanical change that
> shouldn't be any harder for virtio-scsi. Whether we can optimise even
> more by integration the device more with coroutines might be a different
> problem, but at this point you've already got rid of AIOCBs.
Because I/O is done by the generic SCSI code, so you'd have to modify
that and the DMA helpers. And the generic SCSI code is itself written
asynchronously in order to support HBAs that use a bounce buffer.
Paolo
next prev parent reply other threads:[~2014-11-28 19:58 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-28 14:12 [Qemu-devel] [PATCH 0/7] coroutine: optimizations Paolo Bonzini
2014-11-28 14:12 ` [Qemu-devel] [PATCH 1/7] coroutine-ucontext: use __thread Paolo Bonzini
2014-11-28 14:28 ` Peter Maydell
2014-11-28 14:45 ` Markus Armbruster
2014-11-28 15:36 ` Kevin Wolf
2014-11-28 14:12 ` [Qemu-devel] [PATCH 2/7] qemu-thread: add per-thread atexit functions Paolo Bonzini
2014-11-28 14:12 ` [Qemu-devel] [PATCH 3/7] test-coroutine: avoid overflow on 32-bit systems Paolo Bonzini
2014-12-01 1:28 ` Ming Lei
2014-12-01 12:41 ` Paolo Bonzini
2014-12-02 1:20 ` Ming Lei
2014-11-28 14:12 ` [Qemu-devel] [PATCH 4/7] QSLIST: add lock-free operations Paolo Bonzini
2014-11-28 14:12 ` [Qemu-devel] [PATCH 5/7] coroutine: rewrite pool to avoid mutex Paolo Bonzini
2014-11-28 16:40 ` Kevin Wolf
2014-11-28 17:30 ` Paolo Bonzini
2014-11-28 17:31 ` Paolo Bonzini
2014-11-28 18:34 ` Kevin Wolf
2014-11-28 19:57 ` Paolo Bonzini [this message]
2014-11-28 14:12 ` [Qemu-devel] [PATCH 6/7] coroutine: drop qemu_coroutine_adjust_pool_size Paolo Bonzini
2014-11-28 14:12 ` [Qemu-devel] [PATCH 7/7] coroutine: try harder not to delete coroutines Paolo Bonzini
2014-11-28 20:52 ` Peter Lieven
2014-11-29 14:27 ` Paolo Bonzini
2014-11-29 21:28 ` Peter Lieven
2014-11-29 14:28 ` Paolo Bonzini
2014-12-01 5:55 ` [Qemu-devel] [PATCH 0/7] coroutine: optimizations Ming Lei
2014-12-01 7:05 ` Peter Lieven
2014-12-01 7:46 ` Ming Lei
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