From: Rusty Russell <rusty@rustcorp.com.au>
To: Asias He <asias@redhat.com>
Cc: kvm@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
Sasha Levin <levinsasha928@gmail.com>,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 3/3] virtio-blk: Add bio-based IO path for virtio-blk
Date: Wed, 04 Jul 2012 12:10:42 +0930 [thread overview]
Message-ID: <87lij0w8np.fsf@rustcorp.com.au> (raw)
In-Reply-To: <4FF23F4B.2040803@redhat.com>
On Tue, 03 Jul 2012 08:39:39 +0800, Asias He <asias@redhat.com> wrote:
> On 07/02/2012 02:41 PM, Rusty Russell wrote:
> > Sure, our guest merging might save us 100x as many exits as no merging.
> > But since we're not doing many requests, does it matter?
>
> We can still have many requests with slow devices. The number of
> requests depends on the workload in guest. E.g. 512 IO threads in guest
> keeping doing IO.
You can have many requests outstanding. But if the device is slow, the
rate of requests being serviced must be low.
Am I misunderstanding something? I thought if you could have a high
rate of requests, it's not a slow device.
Cheers,
Rusty.
WARNING: multiple messages have this Message-ID (diff)
From: Rusty Russell <rusty@rustcorp.com.au>
To: Asias He <asias@redhat.com>
Cc: Sasha Levin <levinsasha928@gmail.com>,
dlaor@redhat.com, kvm@vger.kernel.org,
"Michael S. Tsirkin" <mst@redhat.com>,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 3/3] virtio-blk: Add bio-based IO path for virtio-blk
Date: Wed, 04 Jul 2012 12:10:42 +0930 [thread overview]
Message-ID: <87lij0w8np.fsf@rustcorp.com.au> (raw)
In-Reply-To: <4FF23F4B.2040803@redhat.com>
On Tue, 03 Jul 2012 08:39:39 +0800, Asias He <asias@redhat.com> wrote:
> On 07/02/2012 02:41 PM, Rusty Russell wrote:
> > Sure, our guest merging might save us 100x as many exits as no merging.
> > But since we're not doing many requests, does it matter?
>
> We can still have many requests with slow devices. The number of
> requests depends on the workload in guest. E.g. 512 IO threads in guest
> keeping doing IO.
You can have many requests outstanding. But if the device is slow, the
rate of requests being serviced must be low.
Am I misunderstanding something? I thought if you could have a high
rate of requests, it's not a slow device.
Cheers,
Rusty.
next prev parent reply other threads:[~2012-07-04 2:40 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-18 6:53 [PATCH v2 0/3] Improve virtio-blk performance Asias He
2012-06-18 6:53 ` Asias He
2012-06-18 6:53 ` [PATCH 1/3] block: Introduce __blk_segment_map_sg() helper Asias He
2012-06-18 6:53 ` Asias He
2012-06-18 21:31 ` Tejun Heo
2012-06-18 21:31 ` Tejun Heo
2012-06-19 2:02 ` Asias He
2012-06-19 2:02 ` Asias He
2012-06-19 18:00 ` Tejun Heo
2012-06-19 18:00 ` Tejun Heo
2012-06-18 6:53 ` [PATCH v2 2/3] block: Add blk_bio_map_sg() helper Asias He
2012-06-18 6:53 ` Asias He
2012-06-18 6:53 ` [PATCH 3/3] virtio-blk: Add bio-based IO path for virtio-blk Asias He
2012-06-18 6:53 ` Asias He
2012-06-18 7:46 ` Rusty Russell
2012-06-18 7:46 ` Rusty Russell
2012-06-18 8:03 ` Asias He
2012-06-18 8:03 ` Asias He
2012-06-18 10:05 ` Rusty Russell
2012-06-18 10:05 ` Rusty Russell
2012-06-18 11:14 ` Dor Laor
2012-06-18 11:14 ` Dor Laor
2012-06-18 11:39 ` Sasha Levin
2012-06-18 11:39 ` Sasha Levin
2012-06-19 2:51 ` Asias He
2012-06-19 2:51 ` Asias He
2012-06-19 6:21 ` Dor Laor
2012-06-19 6:21 ` Dor Laor
2012-06-20 4:46 ` Asias He
2012-06-20 4:46 ` Asias He
2012-06-21 9:49 ` Dor Laor
2012-06-21 9:49 ` Dor Laor
2012-07-01 23:54 ` Rusty Russell
2012-07-01 23:54 ` Rusty Russell
2012-07-02 2:45 ` Asias He
2012-07-02 2:45 ` Asias He
2012-07-02 6:41 ` Rusty Russell
2012-07-02 6:41 ` Rusty Russell
2012-07-03 0:39 ` Asias He
2012-07-03 0:39 ` Asias He
2012-07-04 2:40 ` Rusty Russell [this message]
2012-07-04 2:40 ` Rusty Russell
2012-07-06 1:03 ` Asias He
2012-07-06 1:03 ` Asias He
2012-07-03 13:31 ` Paolo Bonzini
2012-07-03 13:31 ` Paolo Bonzini
2012-07-03 14:02 ` Asias He
2012-07-03 14:02 ` Asias He
2012-07-03 14:22 ` Ronen Hod
2012-07-03 14:22 ` Ronen Hod
2012-07-03 14:28 ` Dor Laor
2012-07-03 14:28 ` Dor Laor
2012-07-04 14:10 ` Paolo Bonzini
2012-07-04 14:10 ` Paolo Bonzini
2012-06-18 21:28 ` Tejun Heo
2012-06-18 21:28 ` Tejun Heo
2012-06-19 2:39 ` Asias He
2012-06-19 2:39 ` Asias He
2012-06-18 10:13 ` Michael S. Tsirkin
2012-06-18 10:13 ` Michael S. Tsirkin
2012-06-19 2:21 ` Asias He
2012-06-19 2:21 ` Asias He
2012-06-18 9:37 ` Stefan Hajnoczi
2012-06-18 9:37 ` Stefan Hajnoczi
2012-06-18 10:21 ` Michael S. Tsirkin
2012-06-18 10:21 ` Michael S. Tsirkin
2012-06-18 10:45 ` Stefan Hajnoczi
2012-06-18 10:45 ` Stefan Hajnoczi
2012-06-19 2:30 ` Asias He
2012-06-19 2:30 ` Asias He
2012-06-18 9:14 ` [PATCH v2 0/3] Improve virtio-blk performance Stefan Hajnoczi
2012-06-18 9:14 ` Stefan Hajnoczi
2012-06-18 9:39 ` Asias He
2012-06-18 9:39 ` Asias He
2012-06-18 10:58 ` Stefan Hajnoczi
2012-06-18 10:58 ` Stefan Hajnoczi
2012-06-19 4:24 ` Asias He
2012-06-19 4:24 ` Asias He
2012-06-19 10:14 ` Stefan Hajnoczi
2012-06-19 10:14 ` Stefan Hajnoczi
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