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Re: [Qemu-devel] About QEMU BQL and dirty log switch in Migration
From: |
Yang Hongyang |
Subject: |
Re: [Qemu-devel] About QEMU BQL and dirty log switch in Migration |
Date: |
Mon, 24 Apr 2017 20:13:27 +0800 |
User-agent: |
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 |
On 2017/4/24 20:06, Juan Quintela wrote:
> Yang Hongyang <address@hidden> wrote:
>> Hi all,
>>
>> We found dirty log switch costs more then 13 seconds while migrating
>> a 4T memory guest, and dirty log switch is currently protected by QEMU
>> BQL. This causes guest freeze for a long time when switching dirty log on,
>> and the migration downtime is unacceptable.
>> Are there any chance to optimize the time cost for dirty log switch
>> operation?
>> Or move the time consuming operation out of the QEMU BQL?
>
> Hi
>
> Could you specify what do you mean by dirty log switch?
> The one inside kvm?
> The merge between kvm one and migration bitmap?
The call of the following functions:
memory_global_dirty_log_start/stop();
>
> Thanks, Juan.
>
--
Thanks,
Yang