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Date: Fri, 11 Oct 2013 09:35:46 +0200
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Subject: Re: [Qemu-devel] [PATCH] block/iscsi: introduce bdrv_co_{readv,
	writev, flush_to_disk}
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To: Kevin Wolf <kwolf@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>
Cc: ronniesahlberg@gmail.com, qemu-devel@nongnu.org, stefanha@redhat.com

On 08.10.2013 14:39, Kevin Wolf wrote:
> Am 08.10.2013 um 14:35 hat Paolo Bonzini geschrieben:
>> Il 08/10/2013 14:33, Kevin Wolf ha scritto:
>>>>>>> this converts read, write and flush functions from aio to coroutines.
>>>>> I'm not sure it's already the time for this...  Cancellation sucks in
>>>>> QEMU, and this is going to make things even worse.
>>> Not sure what you're referring to. If you mean iscsi_aio_cancel(), isn't
>>> it dead code anyway since we changed block.c to use coroutines for
>>> everything? bdrv_co_io_em() even throws the acb away, so even if you
>>> wanted, there's no way to cancel the request even today.
>> SCSI tries to use cancellation, and this results in VCPU threads
>> starving all other threads.  So I would like to introduce cancellation
>> points for coroutines.
> Sounds like a nice thing to have, but it's unrelated to this patch.
> Cancellation means waiting for request completion before and after the
> patch.
Is there anything I can contribute or is this all outside the iscsi driver?