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Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations |
Date: |
Thu, 15 Mar 2012 10:36:23 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:10.0.1) Gecko/20120216 Thunderbird/10.0.1 |
Il 15/03/2012 01:42, Richard Laager ha scritto:
>> > It is worse in that we do not want the hardware parameters exposed to the
>> > guest to change behind the scenes, except if you change the machine type
>> > or if you use the default unversioned type.
> You're saying that discard_granularity and discard_zeros_data need to be
> properties of the machine type? If you start with that as a requirement,
> I can see why you want to always report discard_granularity=512 &
> discard_zeros_data=1. But that design has many downsides. I'm not
> convinced that discard_granularity and discard_zeros_data need to be
> properties of the machine type. Why do you feel that's necessary? What's
> the harm in those properties changing across QEMU startups (i.e. guest
> boots)?
Changing across guest boots is a minor problem, but changing across
migration must be avoided at all costs.
BTW, after this discussion I think we can instead report
discard_granularity = 512 and discard_zeroes_data=0 and get most of the
benefit, at least on file-backed storage.
Paolo
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, (continued)
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Kevin Wolf, 2012/03/14
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Paolo Bonzini, 2012/03/14
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Kevin Wolf, 2012/03/14
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Christoph Hellwig, 2012/03/24
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Christoph Hellwig, 2012/03/24
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Richard Laager, 2012/03/26
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Christoph Hellwig, 2012/03/24
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Daniel P. Berrange, 2012/03/26
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Christoph Hellwig, 2012/03/26
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Richard Laager, 2012/03/14
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations,
Paolo Bonzini <=
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Richard Laager, 2012/03/15
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Paolo Bonzini, 2012/03/16
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Christoph Hellwig, 2012/03/24
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Richard Laager, 2012/03/26
- Re: [Qemu-devel] [RFC PATCH 06/17] block: use bdrv_{co, aio}_discard for write_zeroes operations, Christoph Hellwig, 2012/03/27
[Qemu-devel] [RFC PATCH 04/17] qed: implement bdrv_aio_discard, Paolo Bonzini, 2012/03/08
[Qemu-devel] [RFC PATCH 10/17] ide/scsi: add discard_zeroes_data property, Paolo Bonzini, 2012/03/08