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Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on c
From: |
Peter Lieven |
Subject: |
Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert |
Date: |
Wed, 17 Jul 2013 19:48:39 +0200 |
Am 17.07.2013 um 19:04 schrieb Paolo Bonzini <address@hidden>:
> Il 17/07/2013 19:02, Peter Lieven ha scritto:
>> For Disks we always use read/write16 so i think we Should also use
>> writesame16. Or not?
>
> Yes.
>
> Remember you can still use UNMAP if LBPRZ=0.
I can always use it if writesame is not available, but in this case
bdi->discard_zeroes must be 0.
Maybe we should call it discard_writes_zeroes or similar.
Discard_zeroes is sth that should only indicate if lbprz == 1. At least if we
refer to the Linux ioctl. We could include both in BDI.
Peter
>
> Paolo
>
>> Von meinem iPhone gesendet
>>
>> Am 17.07.2013 um 18:31 schrieb ronnie sahlberg <address@hidden>:
>>
>>> On Wed, Jul 17, 2013 at 9:27 AM, Paolo Bonzini <address@hidden> wrote:
>>>> Il 17/07/2013 17:54, ronnie sahlberg ha scritto:
>>>>> I think it is reasonable to assume that IF LBPRZ==1 and IF it is an
>>>>> "optimal unmap request" then the blocks will become unmapped and they
>>>>> will read back as 0.
>>>>
>>>> Yes, but it is not reasonable to assume that bdrv_discard will only
>>>> receive "optimal" requests. Thus, using WRITE SAME for LBPRZ=1, and not
>>>> exposing LBPRZ=1 if LBPWS=0 (may also use LBPWS10 depending on the
>>>> capacity), is the safer thing to do.
>>>>
>>>> Paolo
>>>
>>> ACK.
>>>
>>> WRITESAME10/16 with UNMAP flag set is probably best.
>
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, (continued)
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Kevin Wolf, 2013/07/17
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, ronnie sahlberg, 2013/07/17
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Paolo Bonzini, 2013/07/17
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, ronnie sahlberg, 2013/07/17
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Peter Lieven, 2013/07/17
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Paolo Bonzini, 2013/07/17
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert,
Peter Lieven <=
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Paolo Bonzini, 2013/07/17
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Kevin Wolf, 2013/07/18
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Paolo Bonzini, 2013/07/18
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Kevin Wolf, 2013/07/18
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Peter Lieven, 2013/07/18
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Paolo Bonzini, 2013/07/18
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Peter Lieven, 2013/07/18
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Paolo Bonzini, 2013/07/18
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Peter Lieven, 2013/07/18
- Re: [Qemu-devel] [PATCH 4/4] qemu-img: conditionally discard target on convert, Paolo Bonzini, 2013/07/18