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Re: [Qemu-block] [RFC] Re-evaluating subcluster allocation for qcow2 ima
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-block] [RFC] Re-evaluating subcluster allocation for qcow2 images |
Date: |
Fri, 28 Jun 2019 11:20:57 +0200 |
User-agent: |
Mutt/1.11.3 (2019-02-01) |
Am 27.06.2019 um 17:42 hat Alberto Garcia geschrieben:
> On Thu 27 Jun 2019 05:38:56 PM CEST, Alberto Garcia wrote:
> >> I would consider 64k cluster/8k subcluster as too extreme for me.
>
> I forgot to add: this 64k/8k ratio is only with my current prototype.
>
> In practice if we go with the 128-bit L2 entries we would have 64
> subclusters per cluster, or 32 if we want to have a separate
> QCOW_OFLAG_ZERO for each subcluster (would we need this?).
Yes, I think we'd want to have a separate zero flag for each subcluster.
Otherwise, when writing to a zero cluster, you'd have to COW the whole
supercluster again. And you'd have to fall back to explicit writes of a
zeroed buffer rather than using efficient operations more often.
Kevin
- [Qemu-block] [RFC] Re-evaluating subcluster allocation for qcow2 images, Alberto Garcia, 2019/06/27
- Re: [Qemu-block] [RFC] Re-evaluating subcluster allocation for qcow2 images, Denis Lunev, 2019/06/27
- Re: [Qemu-block] [RFC] Re-evaluating subcluster allocation for qcow2 images, Alberto Garcia, 2019/06/27
- Re: [Qemu-block] [RFC] Re-evaluating subcluster allocation for qcow2 images, Alberto Garcia, 2019/06/27
- Re: [Qemu-block] [RFC] Re-evaluating subcluster allocation for qcow2 images,
Kevin Wolf <=
- Re: [Qemu-block] [RFC] Re-evaluating subcluster allocation for qcow2 images, Alberto Garcia, 2019/06/28
- Re: [Qemu-block] [RFC] Re-evaluating subcluster allocation for qcow2 images, Kevin Wolf, 2019/06/28
- Re: [Qemu-block] [RFC] Re-evaluating subcluster allocation for qcow2 images, Alberto Garcia, 2019/06/28
- Re: [Qemu-block] [RFC] Re-evaluating subcluster allocation for qcow2 images, Kevin Wolf, 2019/06/28
- Re: [Qemu-block] [RFC] Re-evaluating subcluster allocation for qcow2 images, Alberto Garcia, 2019/06/28
- Re: [Qemu-block] [RFC] Re-evaluating subcluster allocation for qcow2 images, Denis Lunev, 2019/06/27
- Re: [Qemu-block] [RFC] Re-evaluating subcluster allocation for qcow2 images, Alberto Garcia, 2019/06/28
- Re: [Qemu-block] [RFC] Re-evaluating subcluster allocation for qcow2 images, Denis Lunev, 2019/06/28
- Re: [Qemu-block] [RFC] Re-evaluating subcluster allocation for qcow2 images, Kevin Wolf, 2019/06/28
- Re: [Qemu-block] [RFC] Re-evaluating subcluster allocation for qcow2 images, Alberto Garcia, 2019/06/28