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Re: [Qemu-devel] [PATCH for-2.8 0/2] pass partial discard requests all t
From: |
Laszlo Ersek |
Subject: |
Re: [Qemu-devel] [PATCH for-2.8 0/2] pass partial discard requests all the way down |
Date: |
Fri, 11 Nov 2016 11:11:55 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 |
On 11/11/16 11:09, Laszlo Ersek wrote:
> On 11/11/16 00:10, Eric Blake wrote:
>> Peter reported a mild regression in qemu 2.7 when targetting the
>> Dell Equallogic iSCSI, which advertizes a preferred and maximum
>> unmap alignment at 15M. In qemu 2.6, trims not aligned to those
>> boundaries still made it to the device, but in 2.7, the block
>> layer is ignoring unaligned portions of guest requests, resulting
>> in fewer blocks being actually trimmed.
>>
>> Since discard is advisary,
>
> advisory?
Ehh, sorry, I missed that this msg wouldn't be committed; it's just the
blurb for the series. The actual commits and the code have the right
spelling. Not gratuitously trying to be a smart-ass...
Laszlo
>> it is borderline if this counts as a
>> bug fix worthy for inclusion in 2.8, or if it should be deferred
>> to 2.9. At any rate, while I was able to test that the patch
>> didn't misbehave for me when I tweaked an NBD setup to force
>> 15M alignment, I am unable to test that it makes an actual
>> difference for Peter's hardware, and that needs to happen before
>> anyone even thinks of applying this.
>>
>> Eric Blake (2):
>> block: Return -ENOTSUP rather than assert on unaligned discards
>> block: Pass unaligned discard requests to drivers
>>
>> block/io.c | 36 +++++++++++++++++++++++-------------
>> block/iscsi.c | 4 +++-
>> block/qcow2.c | 4 ++++
>> block/sheepdog.c | 5 +++--
>> 4 files changed, 33 insertions(+), 16 deletions(-)
>>
>