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Re: [Qemu-block] [PATCH v4 6/7] blkdebug: Add ability to override unmap
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From: |
Eric Blake |
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Subject: |
Re: [Qemu-block] [PATCH v4 6/7] blkdebug: Add ability to override unmap geometries |
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Date: |
Mon, 30 Jan 2017 10:54:01 -0600 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.6.0 |
On 01/28/2017 02:57 PM, Max Reitz wrote:
> On 20.12.2016 20:15, Eric Blake wrote:
>> Make it easier to simulate various unusual hardware setups (for
>> example, recent commits 3482b9b and b8d0a98 affect the Dell
>> Equallogic iSCSI with its 15M preferred and maximum unmap and
>> write zero sizing, or b2f95fe deals with the Linux loopback
>> block device having a max_transfer of 64k), by allowing blkdebug
>> to wrap any other device with further restrictions on various
>> alignments.
>>
>> Signed-off-by: Eric Blake <address@hidden>
>>
>> +++ b/qapi/block-core.json
>> @@ -2072,6 +2072,26 @@
>> # @align: #optional required alignment for requests in bytes,
>> # must be power of 2, or 0 for default
>> #
>> +# @max-transfer: #optional maximum size for I/O transfers in bytes,
>> +# must be multiple of @align
>
> ...and the file's request alignment. Should that be noted here?
As in - if we set @align to 1, but the underlying file still requires an
alignment of 512, then @max-transfer has to be at least 512. Yeah, that
makes sense to document.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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