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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4FCF4E90.7050806@redhat.com \
--to=pbonzini@redhat.com \
--cc=asias.hejun@gmail.com \
--cc=gorcunov@gmail.com \
--cc=kvm@vger.kernel.org \
--cc=levinsasha928@gmail.com \
--cc=mingo@elte.hu \
--cc=penberg@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.