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Re: [Qemu-devel] [PATCH V2] add migration capability to bypass the share
From: |
Lai Jiangshan |
Subject: |
Re: [Qemu-devel] [PATCH V2] add migration capability to bypass the shared memory |
Date: |
Thu, 11 Aug 2016 22:31:45 +0800 |
On Thu, Aug 11, 2016 at 3:11 PM, Li, Liang Z <address@hidden> wrote:
>> >>
>> >> I might have missed something, could you tell me more?
>> >>
>> >> void bitmap_set(unsigned long *map, long start, long nr); I think the
>> >> @start and @nr are both the number of the bits.
>> >>
>> >> thanks,
>> >> Lai
>> >
>> > You are right, I have make a mistake by checking the code. Sorry for the
>> noise.
>> >
>> > BTW. Is it possible to bypass the shared block in the
>> 'ram_find_and_save_block'?
>> > I mean no to check if a page is dirty for a shared block, it may make
>> > things
>> faster.
>>
>> Nice spotted. That would make things faster. But once there we could split
>> the bitmap by ramblock, and the migration_dirty_pages also per block, that
>> would make all the searchs faster, and adding/removing blocks of ram much
>> easier. If we enter optimizing that function, we could really do much better
>> that the "again" parameter that we have right now.
>>
>> Later, Juan.
This patch focuses on the core thing: adding the ability to bypass
migrating the memory.
I don't want to add further optimization for it now.
I hope this patch merged solo and earlier.
optimization patches can be sent after this patch accepted.
>
> Did some experiment with an 8GB VM.
> Total time: 93ms
> Setup: 70ms
> Downtime: 6ms
>
> So most of the time spend on Setup stage, and most of the time spend on
> setup stage is starting dirty page logging.
> How about not start dirty page logging for shared blocks? then it's possible
> to shorten the total time to about 30ms.
bypass migrating the memory includes
bypass copying&sending the memory (this patch, save seconds)
bypass dirty page logging (save ten of milliseconds)
bypass other thing??
30ms is a huge part of the 130ms of the hyperhq cases.
We definitely need it, I once tried it at the beginning, but it is a
little complicated for me. So I focus the the major part now.
Thanks,
Lai
>
> Liang
>
>
>
>
>
- [Qemu-devel] [PATCH] add migration capability to bypass the shared memory, Lai Jiangshan, 2016/08/09
- Re: [Qemu-devel] [PATCH] add migration capability to bypass the shared memory, no-reply, 2016/08/09
- Re: [Qemu-devel] [PATCH] add migration capability to bypass the shared memory, Dr. David Alan Gilbert, 2016/08/09
- [Qemu-devel] [PATCH V2] add migration capability to bypass the shared memory, Lai Jiangshan, 2016/08/09
- Re: [Qemu-devel] [PATCH V2] add migration capability to bypass the shared memory, Fam Zheng, 2016/08/09
- Re: [Qemu-devel] [PATCH V2] add migration capability to bypass the shared memory, Li, Liang Z, 2016/08/09
- Re: [Qemu-devel] [PATCH V2] add migration capability to bypass the shared memory, Lai Jiangshan, 2016/08/09
- Re: [Qemu-devel] [PATCH V2] add migration capability to bypass the shared memory, Li, Liang Z, 2016/08/10
- Re: [Qemu-devel] [PATCH V2] add migration capability to bypass the shared memory, Juan Quintela, 2016/08/10
- Re: [Qemu-devel] [PATCH V2] add migration capability to bypass the shared memory, Li, Liang Z, 2016/08/11
- Re: [Qemu-devel] [PATCH V2] add migration capability to bypass the shared memory,
Lai Jiangshan <=
- Re: [Qemu-devel] [PATCH V2] add migration capability to bypass the shared memory, Lai Jiangshan, 2016/08/11
- Re: [Qemu-devel] [PATCH V2] add migration capability to bypass the shared memory, Li, Liang Z, 2016/08/12
- Re: [Qemu-devel] [PATCH V2] add migration capability to bypass the shared memory, Lai Jiangshan, 2016/08/12
Re: [Qemu-devel] [PATCH] add migration capability to bypass the shared memory, Lai Jiangshan, 2016/08/09
Re: [Qemu-devel] [PATCH] add migration capability to bypass the shared memory, Juan Quintela, 2016/08/10