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Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics |
Date: |
Wed, 09 Jan 2013 12:10:31 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 |
Il 09/01/2013 11:58, Liu Yuan ha scritto:
> On 01/09/2013 06:46 PM, Liu Yuan wrote:
>> I'll collect some numbers on it.
>
> Well, when I use hdparm -W 0 /dev/vdx to choose the writethrough cache
> in the Guest (virtio disk), it says:
>
> address@hidden:~$ sudo hdparm -W 0 /dev/vdb
>
> /dev/vdb:
> setting drive write-caching to 0 (off)
> HDIO_DRIVE_CMD(identify) failed: Inappropriate ioctl for device
> HDIO_DRIVE_CMD(flushcache) failed: Inappropriate ioctl for device
> HDIO_DRIVE_CMD(setcache) failed: Inappropriate ioctl for device
> HDIO_DRIVE_CMD(identify) failed: Inappropriate ioctl for device
> HDIO_DRIVE_CMD(flushcache) failed: Inappropriate ioctl for device
> HDIO_DRIVE_CMD(identify) failed: Inappropriate ioctl for device
>
> Do I need extra flags to enable WCE?
"hdparm" is specific for IDE devices. sysfs is supported by SCSI
(including IDE with libata, and virtio-scsi) and virtio-blk.
You can use this for SCSI:
echo 'write back' > /sys/block/sda/device/scsi_disk/*/cache_type
and a similar command for virtio-blk.
Paolo
> Both Guest and Host kernel is 3.7 and I start QEMU by following command:
>
> $ qemu-system-x86_64 --enable-kvm -drive
> file=~/images/test1,if=virtio,cache=writeback -smp 2 -cpu host -m 1024
> -drive file=sheepdog:test,if=virtio,cache=writeback
>
> Thanks,
> Yuan
>
>
- Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics, (continued)
- Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics, Kevin Wolf, 2013/01/08
- Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics, Liu Yuan, 2013/01/08
- Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics, Kevin Wolf, 2013/01/08
- Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics, Liu Yuan, 2013/01/08
- Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics, Liu Yuan, 2013/01/08
- Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics, Paolo Bonzini, 2013/01/09
- Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics, Liu Yuan, 2013/01/09
- Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics, Paolo Bonzini, 2013/01/09
- Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics, Liu Yuan, 2013/01/09
- Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics, Liu Yuan, 2013/01/09
- Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics,
Paolo Bonzini <=
- Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics, Liu Yuan, 2013/01/09
- Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics, Liu Yuan, 2013/01/09
- Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics, Liu Yuan, 2013/01/09
- Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics, Kevin Wolf, 2013/01/09
- Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics, Liu Yuan, 2013/01/09
- Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics, Paolo Bonzini, 2013/01/09
- Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics, Liu Yuan, 2013/01/10
- Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics, MORITA Kazutaka, 2013/01/11
- Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics, Liu Yuan, 2013/01/11
- Re: [Qemu-devel] [PATCH] sheepdog: implement direct write semantics, Paolo Bonzini, 2013/01/11