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Re: [Qemu-devel] [PATCH] block: fix big write
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH] block: fix big write |
Date: |
Wed, 10 Dec 2014 10:56:12 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 |
On 10/12/2014 02:41, Ming Lei wrote:
> On Wed, Dec 10, 2014 at 1:45 AM, Paolo Bonzini <address@hidden> wrote:
>>
>>
>> On 08/12/2014 08:19, Ming Lei wrote:
>>>>>
>>>>> Alternatively, I'd accept a SCSI patch setting max_ws_blocks and friends
>>>>> to 2GB - 1 block.
>>> It should be better to not introduce the limit and split the writes
>>> into size of 2GB - 1 block since there is only the limit for write zero.
>>
>> Why? That's exactly what the max_ws_blocks is for, and there's code in
>> the guest already to do the split. We're talking about 2GB, not 1MB.
>
> The split in write same does not cover write zero, and that is the problem.
> Otherwise write same just works fine. That said write same of QEMU SCSI
> can work well without max write same sectors limit.
>
> If we introduce the limit of max write same sectors, this limit will be put
> on both write zero and write non-zero path.
Yeah, but the 2GB limit happens also for the regular I/O path. The
quirk is that it doesn't happen for non-zero WRITE SAME, not the other
way round.
> Also "MAXIMUM WRITE SAME LENGTH" is just introduced on sbc3r35
> in Jan, 2013, and some old host drivers may not support it, and not using
> the limit should have better compatibility.
Again, we're talking of 2GB and this is something that should never
happen in practice.
I'll write the patch myself.
Paolo
> Thanks,
> Ming Lei
>
>
- [Qemu-devel] [PATCH] block: fix big write, Ming Lei, 2014/12/05
- Re: [Qemu-devel] [PATCH] block: fix big write, Paolo Bonzini, 2014/12/05
- Re: [Qemu-devel] [PATCH] block: fix big write, Ming Lei, 2014/12/08
- Re: [Qemu-devel] [PATCH] block: fix big write, Paolo Bonzini, 2014/12/09
- Re: [Qemu-devel] [PATCH] block: fix big write, Ming Lei, 2014/12/09
- Re: [Qemu-devel] [PATCH] block: fix big write,
Paolo Bonzini <=
- Re: [Qemu-devel] [PATCH] block: fix big write, Ming Lei, 2014/12/10
- Re: [Qemu-devel] [PATCH] block: fix big write, Paolo Bonzini, 2014/12/10
- Re: [Qemu-devel] [PATCH] block: fix big write, Ming Lei, 2014/12/10
- Re: [Qemu-devel] [PATCH] block: fix big write, Paolo Bonzini, 2014/12/10
- Re: [Qemu-devel] [PATCH] block: fix big write, Ming Lei, 2014/12/10
- Re: [Qemu-devel] [PATCH] block: fix big write, Paolo Bonzini, 2014/12/10
Re: [Qemu-devel] [PATCH] block: fix big write, Max Reitz, 2014/12/05