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Re: [Qemu-block] [Qemu-devel] [PATCH 06/16] block: add BDS field to coun
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From: |
Fam Zheng |
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Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH 06/16] block: add BDS field to count in-flight requests |
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Date: |
Wed, 9 Mar 2016 16:00:30 +0800 |
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User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Wed, 03/09 08:43, Paolo Bonzini wrote:
>
>
> On 09/03/2016 04:35, Fam Zheng wrote:
> >> > enum BdrvTrackedRequestType {
> >> > BDRV_TRACKED_READ,
> >> > BDRV_TRACKED_WRITE,
> >> > - BDRV_TRACKED_FLUSH,
> >> > - BDRV_TRACKED_IOCTL,
> >> > BDRV_TRACKED_DISCARD,
> > Okay, so flush and ioctl are not needed, but why is discard different?
>
> Discard can modify the contents of the device, so I think it's safer to
> serialize it against RMW and copy-on-read operations.
Okay, that makes sense, but ioctl like SG_IO can also modify content, no?
Fam