[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH] qemu-img: let qemu-img behave as the manual adv
From: |
Liu Yuan |
Subject: |
Re: [Qemu-devel] [PATCH] qemu-img: let qemu-img behave as the manual advertise |
Date: |
Wed, 11 Apr 2012 22:08:46 +0800 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.28) Gecko/20120313 Thunderbird/3.1.20 |
On 04/11/2012 08:27 PM, Kevin Wolf wrote:
> Am 11.04.2012 12:33, schrieb Kevin Wolf:
>> Am 11.04.2012 12:05, schrieb Liu Yuan:
>>> On 04/11/2012 03:49 PM, Kevin Wolf wrote:
>>>
>>>> I don't agree with this patch. If the documentation says that qemu-img
>>>> always uses writeback, then the documentation must be fixed.
>>>>
>>>> We really don't care about flushes during an image conversion. It should
>>>> just go as fast as it can. If any error happens in the middle, you'll
>>>> have to throw the image away anyway, because it contains only half of
>>>> what you need. So not having flushed doesn't really make any difference.
>>>>
>>>> As soon as a guest begins using the image with data that we really care
>>>> about, it's probably running in a VM with non-unsafe mode, and then it
>>>> gets flushed.
>>>
>>>
>>> But we can set cache mode for qemu-img convert. So at least if we set
>>> explicitly with other modes(for e.g, writeback) that ask to flush the
>>> dirty bits, I think we should call brdv_flush().
>>>
>>> If you agree, I'll update the patch with this modification.
>>
>> Yes, adding the flush is fine, I just wouldn't change the default cache
>> mode.
>
> On second thought, wouldn't make it more sense to add the flush in
> bdrv_close(), so that all callers get it?
>
Hmm, yes, if high level bdrv_close() calls bdrv_flush() internally, we
can safely call bdrv_close() from users (qemu-img) to ensure data
writeback with proper cache mode.
Thanks,
Yuan
Re: [Qemu-devel] [PATCH] qemu-img: let qemu-img behave as the manual advertise, Kevin Wolf, 2012/04/11
- Re: [Qemu-devel] [PATCH] qemu-img: let qemu-img behave as the manual advertise, Liu Yuan, 2012/04/11
- Re: [Qemu-devel] [PATCH] qemu-img: let qemu-img behave as the manual advertise, Kevin Wolf, 2012/04/11
- Re: [Qemu-devel] [PATCH] qemu-img: let qemu-img behave as the manual advertise, Kevin Wolf, 2012/04/11
- Re: [Qemu-devel] [PATCH] qemu-img: let qemu-img behave as the manual advertise,
Liu Yuan <=
- [Qemu-devel] [PATCH v2] qemu-img: let 'qemu-img convert' flush data, Liu Yuan, 2012/04/11
- Re: [Qemu-devel] [PATCH v2] qemu-img: let 'qemu-img convert' flush data, Paolo Bonzini, 2012/04/11
- Re: [Qemu-devel] [PATCH v2] qemu-img: let 'qemu-img convert' flush data, Liu Yuan, 2012/04/11
- Re: [Qemu-devel] [PATCH v2] qemu-img: let 'qemu-img convert' flush data, Liu Yuan, 2012/04/12
- Re: [Qemu-devel] [PATCH v2] qemu-img: let 'qemu-img convert' flush data, Kevin Wolf, 2012/04/13
- [Qemu-devel] [PATCH v3] qemu-img: let 'qemu-img convert' flush data, Liu Yuan, 2012/04/13
- Re: [Qemu-devel] [PATCH v3] qemu-img: let 'qemu-img convert' flush data, Liu Yuan, 2012/04/20
- Re: [Qemu-devel] [PATCH v3] qemu-img: let 'qemu-img convert' flush data, Kevin Wolf, 2012/04/20
- [Qemu-devel] [PATCH v4] qemu-img: let 'qemu-img convert' flush data, Liu Yuan, 2012/04/20
- Re: [Qemu-devel] [PATCH v4] qemu-img: let 'qemu-img convert' flush data, Kevin Wolf, 2012/04/20