[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH] block-raw: Make cache=off default again
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] [PATCH] block-raw: Make cache=off default again |
Date: |
Tue, 23 Jun 2009 13:46:13 +0200 |
User-agent: |
Thunderbird 2.0.0.21 (X11/20090320) |
Jamie Lokier schrieb:
> Kevin Wolf wrote:
>> What happens with virtio I still need to understand. Obviously, as soon
>> as virtio decides to fall back to 4k requests, performance becomes
>> terrible.
>
> Does emulating a disk with 4k sector size instead of 512 bytes help this?
I just changed the virtio_blk code to always do the
blk_queue_hardsect_size with 4096, didn't change the behaviour.
I'm not sure if I have mentioned it in this thread: We have found that
it helps to use the deadline elevator instead of cfq in either the host
or the guest. I would accept this if it would only help when it's
changed in the guest (after all, I don't know the Linux block layer very
well), but I certainly don't understand how the host elevator could
change the guest request sizes - and noone else on the internal mailing
lists had an explanation either.
Kevin
- [Qemu-devel] [PATCH] block-raw: Make cache=off default again, Kevin Wolf, 2009/06/22
- Re: [Qemu-devel] [PATCH] block-raw: Make cache=off default again, Christoph Hellwig, 2009/06/22
- Re: [Qemu-devel] [PATCH] block-raw: Make cache=off default again, Kevin Wolf, 2009/06/22
- Re: [Qemu-devel] [PATCH] block-raw: Make cache=off default again, Avi Kivity, 2009/06/22
- Re: [Qemu-devel] [PATCH] block-raw: Make cache=off default again, Kevin Wolf, 2009/06/22
- Re: [Qemu-devel] [PATCH] block-raw: Make cache=off default again, Avi Kivity, 2009/06/22
- Re: [Qemu-devel] [PATCH] block-raw: Make cache=off default again, Kevin Wolf, 2009/06/22
- Re: [Qemu-devel] [PATCH] block-raw: Make cache=off default again, Jamie Lokier, 2009/06/23
- Re: [Qemu-devel] [PATCH] block-raw: Make cache=off default again,
Kevin Wolf <=
- Re: [Qemu-devel] [PATCH] block-raw: Make cache=off default again, Jamie Lokier, 2009/06/24
- Re: [Qemu-devel] [PATCH] block-raw: Make cache=off default again, Kevin Wolf, 2009/06/25
- Re: [Qemu-devel] [PATCH] block-raw: Make cache=off default again, Christoph Hellwig, 2009/06/22
- Re: [Qemu-devel] [PATCH] block-raw: Make cache=off default again, Kevin Wolf, 2009/06/22
- Re: [Qemu-devel] [PATCH] block-raw: Make cache=off default again, Avi Kivity, 2009/06/22
Re: [Qemu-devel] [PATCH] block-raw: Make cache=off default again, Anthony Liguori, 2009/06/22