From: Stefan Hajnoczi <stefanha@gmail.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: krister@redhat.com, Stefan Hajnoczi <stefanha@redhat.com>,
qemu-devel@nongnu.org, Andrew Theurer <atheurer@redhat.com>,
Fam Zheng <famz@redhat.com>
Subject: Re: [Qemu-devel] [RFC 0/3] aio: experimental virtio-blk polling mode
Date: Tue, 15 Nov 2016 10:32:02 +0000 [thread overview]
Message-ID: <20161115103202.GB4836@stefanha-x1.localdomain> (raw)
In-Reply-To: <7d65b41d-f4f8-0aee-53d5-4d6401fe89e8@redhat.com>
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On Mon, Nov 14, 2016 at 09:52:00PM +0100, Paolo Bonzini wrote:
> On 14/11/2016 21:12, Karl Rister wrote:
> > 256 46,929
> > 512 35,627
> > 1,024 46,477
> > 2,000 35,247
> > 2,048 46,322
> > 4,000 46,540
> > 4,096 46,368
> > 8,000 47,054
> > 8,192 46,671
> > 16,000 46,466
> > 16,384 32,504
> > 32,000 20,620
> > 32,768 20,807
>
> Huh, it breaks down exactly when it should start going faster
> (10^9/46000 = ~21000).
Could it be because we're not breaking the polling loop for BHs, new
timers, or aio_notify()?
Once that is fixed polling should achieve maximum performance when
QEMU_AIO_MAX_POLL_NS is at least as long as the duration of a request.
This is logical if there are enough pinned CPUs so the polling thread
can run flat out.
Stefan
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next prev parent reply other threads:[~2016-11-15 10:32 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-09 17:13 [Qemu-devel] [RFC 0/3] aio: experimental virtio-blk polling mode Stefan Hajnoczi
2016-11-09 17:13 ` [Qemu-devel] [RFC 1/3] aio-posix: add aio_set_poll_handler() Stefan Hajnoczi
2016-11-09 17:30 ` Paolo Bonzini
2016-11-10 10:17 ` Stefan Hajnoczi
2016-11-10 13:20 ` Paolo Bonzini
2016-11-15 20:14 ` Fam Zheng
2016-11-09 17:13 ` [Qemu-devel] [RFC 2/3] virtio: poll virtqueues for new buffers Stefan Hajnoczi
2016-11-09 17:13 ` [Qemu-devel] [RFC 3/3] linux-aio: poll ring for completions Stefan Hajnoczi
2016-11-11 19:59 ` [Qemu-devel] [RFC 0/3] aio: experimental virtio-blk polling mode Karl Rister
2016-11-14 13:53 ` Fam Zheng
2016-11-14 14:52 ` Karl Rister
2016-11-14 16:56 ` Stefan Hajnoczi
2016-11-14 15:26 ` Stefan Hajnoczi
2016-11-14 15:29 ` Paolo Bonzini
2016-11-14 17:06 ` Stefan Hajnoczi
2016-11-14 17:13 ` Fam Zheng
2016-11-14 17:15 ` Paolo Bonzini
2016-11-15 10:36 ` Stefan Hajnoczi
2016-11-16 8:27 ` Fam Zheng
2016-11-14 15:36 ` Karl Rister
2016-11-14 20:12 ` Karl Rister
2016-11-14 20:52 ` Paolo Bonzini
2016-11-15 10:32 ` Stefan Hajnoczi [this message]
2016-11-15 18:45 ` Karl Rister
2016-11-13 6:20 ` no-reply
2016-11-14 14:51 ` Christian Borntraeger
2016-11-14 16:53 ` Stefan Hajnoczi
2016-11-14 14:59 ` Christian Borntraeger
2016-11-14 16:52 ` Stefan Hajnoczi
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