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Re: [Qemu-devel] [PATCH 4/4] block: Cater to iscsi with non-power-of-2 d
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 4/4] block: Cater to iscsi with non-power-of-2 discard |
Date: |
Tue, 25 Oct 2016 14:09:17 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 |
On 25/10/2016 14:03, Peter Lieven wrote:
> Am 01.08.2016 um 11:22 schrieb Paolo Bonzini:
>>
>> On 28/07/2016 04:39, Eric Blake wrote:
>>> On 07/27/2016 01:25 AM, Fam Zheng wrote:
>>>> On Thu, 07/21 13:34, Eric Blake wrote:
>>>>> + max_write_zeroes = max_write_zeroes / alignment * alignment;
>>>> Not using QEMU_ALIGN_DOWN despite patch 3?
>>> Looks like I missed that on the rebase. Can fix if there is a reason for
>>> a respin.
>> Since Stefan acked this, I'm applying the patch and fixing it to use
>> QEMU_ALIGN_DOWN.
>>
>> Paolo
>
> Hi,
>
> I came across a sort of regression we introduced with the dropping of
> head and tail
> of an unaligned discard.
>
> The discard alignment that we use to trim the discard request is just a
> hint.
>
> I learned on the equallogics that a page (which is this unusal 15MB
> large) is
> unallocated even if the discard happens in pieces. E.g. in slices of 1MB
> requests.
>
> From my point of view I would like to restore the old behaviour. What do
> you think?
The right logic should be the one in Linux: if splitting a request, and
the next starting sector would be misaligned, stop the discard at the
previous aligned sector. Otherwise leave everything alone.
Paolo
- Re: [Qemu-devel] [PATCH 4/4] block: Cater to iscsi with non-power-of-2 discard, Peter Lieven, 2016/10/25
- Re: [Qemu-devel] [PATCH 4/4] block: Cater to iscsi with non-power-of-2 discard,
Paolo Bonzini <=
- Re: [Qemu-devel] [PATCH 4/4] block: Cater to iscsi with non-power-of-2 discard, Peter Lieven, 2016/10/25
- Re: [Qemu-devel] [PATCH 4/4] block: Cater to iscsi with non-power-of-2 discard, Paolo Bonzini, 2016/10/25
- Re: [Qemu-devel] [PATCH 4/4] block: Cater to iscsi with non-power-of-2 discard, Peter Lieven, 2016/10/25
- Re: [Qemu-devel] [PATCH 4/4] block: Cater to iscsi with non-power-of-2 discard, Eric Blake, 2016/10/25
- Re: [Qemu-devel] [PATCH 4/4] block: Cater to iscsi with non-power-of-2 discard, Peter Lieven, 2016/10/25
- Re: [Qemu-devel] [PATCH 4/4] block: Cater to iscsi with non-power-of-2 discard, Eric Blake, 2016/10/25
- Re: [Qemu-devel] [PATCH 4/4] block: Cater to iscsi with non-power-of-2 discard, Paolo Bonzini, 2016/10/25
- Re: [Qemu-devel] [PATCH 4/4] block: Cater to iscsi with non-power-of-2 discard, Eric Blake, 2016/10/25