From: Christoph Hellwig <hch@lst.de>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: 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 V4 3/3] virtio-blk: Add bio-based IO path for virtio-blk
Date: Mon, 30 Jul 2012 15:42:47 +0200 [thread overview]
Message-ID: <20120730134247.GA6041@lst.de> (raw)
In-Reply-To: <87a9yim2qg.fsf@rustcorp.com.au>
On Mon, Jul 30, 2012 at 11:25:51AM +0930, Rusty Russell wrote:
> I consider this approach a half-way step. Quick attempts on my laptop
> and I couldn't find a case where the bio path was a loss, but in theory
> if the host wasn't doing any reordering and it was a slow device, you'd
> want the guest to do so.
>
> I'm not sure if current qemu can be configured to do such a thing?
The host kernel will do the I/O scheduling for you unless you explicitly
disable it. And we should be able to assume an administrator will only
disable it when they have a reason for it - if not they'll get worse
performance for non-virtualized workloads as well.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
Asias He <asias@redhat.com>,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org, kvm@vger.kernel.org,
Christoph Hellwig <hch@lst.de>,
Minchan Kim <minchan.kim@gmail.com>
Subject: Re: [PATCH V4 3/3] virtio-blk: Add bio-based IO path for virtio-blk
Date: Mon, 30 Jul 2012 15:42:47 +0200 [thread overview]
Message-ID: <20120730134247.GA6041@lst.de> (raw)
In-Reply-To: <87a9yim2qg.fsf@rustcorp.com.au>
On Mon, Jul 30, 2012 at 11:25:51AM +0930, Rusty Russell wrote:
> I consider this approach a half-way step. Quick attempts on my laptop
> and I couldn't find a case where the bio path was a loss, but in theory
> if the host wasn't doing any reordering and it was a slow device, you'd
> want the guest to do so.
>
> I'm not sure if current qemu can be configured to do such a thing?
The host kernel will do the I/O scheduling for you unless you explicitly
disable it. And we should be able to assume an administrator will only
disable it when they have a reason for it - if not they'll get worse
performance for non-virtualized workloads as well.
next prev parent reply other threads:[~2012-07-30 13:42 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-28 2:21 [PATCH V4 0/3] Improve virtio-blk performance Asias He
2012-07-28 2:21 ` Asias He
2012-07-28 2:21 ` [PATCH V4 1/3] block: Introduce __blk_segment_map_sg() helper Asias He
2012-07-28 2:21 ` [PATCH V4 2/3] block: Add blk_bio_map_sg() helper Asias He
2012-07-28 2:21 ` [PATCH V4 3/3] virtio-blk: Add bio-based IO path for virtio-blk Asias He
2012-07-28 2:21 ` Asias He
2012-07-28 6:35 ` Sasha Levin
2012-07-28 6:35 ` Sasha Levin
2012-07-30 6:27 ` Asias He
2012-07-30 6:27 ` Asias He
2012-07-29 11:11 ` Michael S. Tsirkin
2012-07-29 11:11 ` Michael S. Tsirkin
2012-07-30 1:55 ` Rusty Russell
2012-07-30 1:55 ` Rusty Russell
2012-07-30 13:42 ` Christoph Hellwig [this message]
2012-07-30 13:42 ` Christoph Hellwig
2012-07-30 4:33 ` Asias He
2012-07-30 4:33 ` Asias He
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