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Re: [Qemu-devel] Re: KVM call minutes for Sept 14
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] Re: KVM call minutes for Sept 14 |
Date: |
Wed, 15 Sep 2010 10:30:16 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.12) Gecko/20100907 Fedora/3.0.7-1.fc12 Thunderbird/3.0.7 |
Am 14.09.2010 17:11, schrieb Anthony Liguori:
> On 09/14/2010 09:47 AM, Chris Wright wrote:
>> 0.13
>> - if all goes well...tomorrow
>>
>
> To tag, it may be thursday for announcement. I need to run a regression
> run tonight.
>
>> qed/qcow2
>> - increase concurrency, performance
>>
>
> To achieve performance, a block driver must: 1) support concurrent
> request handling 2) not hold the qemu_mutex for prolonged periods of time.
>
> QED never does (2) and supports (1) in all circumstances except cluster
> allocation today.
>
> qcow2 can do (1) for the data read/write portions of an I/O request.
> All metadata read/write is serialized. It also does (2) for all
> metadata operations and for CoW operations.
>
> These are implementation details though. The real claim of QED is that
> by having fewer IO ops required to satisfy a request, it achieves better
> performance especially since it achieves zero syncs in the cluster
> allocation path. qcow2 has two syncs in the cluster allocation path
> today. One sync is due to the refcount table. Another sync is due to
> the fact that it doesn't require fsck support.
The refcount table sync is the sync that allows not doing an fsck. For a
simple cluster allocation (no L2 allocation, no COW), we only have one
sync (which is still one sync too much in this path, so we must move it).
Kevin
- [Qemu-devel] KVM call minutes for Sept 14, Chris Wright, 2010/09/14
- [Qemu-devel] Re: KVM call minutes for Sept 14, Anthony Liguori, 2010/09/14
- Re: [Qemu-devel] Re: KVM call minutes for Sept 14,
Kevin Wolf <=
- Re: [Qemu-devel] Re: KVM call minutes for Sept 14, Anthony Liguori, 2010/09/15
- Re: [Qemu-devel] Re: KVM call minutes for Sept 14, Kevin Wolf, 2010/09/15
- Re: [Qemu-devel] Re: KVM call minutes for Sept 14, Anthony Liguori, 2010/09/15
- Re: [Qemu-devel] Re: KVM call minutes for Sept 14, Kevin Wolf, 2010/09/15
- Re: [Qemu-devel] Re: KVM call minutes for Sept 14, Anthony Liguori, 2010/09/15
- Re: [Qemu-devel] Re: KVM call minutes for Sept 14, Kevin Wolf, 2010/09/15