From: Paolo Bonzini <pbonzini@redhat.com>
To: Sasha Levin <levinsasha928@gmail.com>
Cc: Asias He <asias.hejun@gmail.com>,
Pekka Enberg <penberg@kernel.org>, Ingo Molnar <mingo@elte.hu>,
Cyrill Gorcunov <gorcunov@gmail.com>,
kvm@vger.kernel.org
Subject: Re: [PATCH] kvm tools: Process virito blk requests in separate thread
Date: Wed, 06 Jun 2012 14:35:28 +0200 [thread overview]
Message-ID: <4FCF4E90.7050806@redhat.com> (raw)
In-Reply-To: <1338826065.3292.10.camel@lappy>
Il 04/06/2012 18:07, Sasha Levin ha scritto:
>> > All blk requests are processed in notify_vq() which is in the context of
>> > ioeventfd thread: ioeventfd__thread(). The processing in notify_vq() may
>> > take a long time to complete and all devices share the single ioeventfd
>> > thead, so this might block other device's notify_vq() being called and
>> > starve other devices.
> We're using native vectored AIO for for processing blk requests, so I'm
> not certain if theres any point in giving the blk device it's own thread
> for handling that.
I never looked at the kvmtool code, but I think Asias has a point. If
the guest submits I/O to lots of devices, they would contend on the
single thread. There was a similar proof of concept patch for QEMU that
provided substantial benefit.
However, it sounds a bit wasteful to have the dedicated thread run with
a second eventfd. Would it be hard to just use the virtio-blk ioeventfd
directly?
Paolo
next prev parent reply other threads:[~2012-06-06 12:35 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-04 15:40 [PATCH] kvm tools: Process virito blk requests in separate thread Asias He
2012-06-04 15:48 ` Cyrill Gorcunov
2012-06-05 0:47 ` Asias He
2012-06-05 6:10 ` Cyrill Gorcunov
2012-06-04 16:07 ` Sasha Levin
2012-06-05 1:03 ` Asias He
2012-06-05 8:14 ` Pekka Enberg
2012-06-06 12:35 ` Paolo Bonzini [this message]
2012-06-07 1:38 ` Asias He
2012-06-07 8:47 ` Paolo Bonzini
2012-06-08 3:30 ` Asias He
2012-06-05 8:15 ` Pekka Enberg
-- strict thread matches above, loose matches on Subject: below --
2011-11-29 14:28 Asias He
2011-11-29 14:36 ` Sasha Levin
2011-11-30 7:21 ` Asias He
2011-12-01 8:48 ` Pekka Enberg
2011-12-01 8:58 ` Sasha Levin
2011-12-01 10:45 ` Pekka Enberg
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