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From: Avi Kivity on 12 Apr 2010 04:40
On 04/12/2010 11:02 AM, Xiao Guangrong wrote:
> - 'vcpu' is not used while mark parent unsync, so remove it
> - if it has alread marked unsync, no need to walk it's parent
>
>

Please separate these two changes.

The optimization looks good. Perhaps it can be done even nicer using
mutually recursive functions (mmu_parent_walk calls mmu_parent_walk_fn
which calls mmu_parent_walk on the parent), but let's not change too
many things at a time.

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From: Xiao Guangrong on 12 Apr 2010 05:00


Avi Kivity wrote:
> On 04/12/2010 11:02 AM, Xiao Guangrong wrote:
>> - 'vcpu' is not used while mark parent unsync, so remove it
>> - if it has alread marked unsync, no need to walk it's parent
>>
>>
>
> Please separate these two changes.
>
> The optimization looks good. Perhaps it can be done even nicer using
> mutually recursive functions (mmu_parent_walk calls mmu_parent_walk_fn
> which calls mmu_parent_walk on the parent), but let's not change too
> many things at a time.

OK, i'll separate it in the next version

Thanks,
Xiao
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From: Marcelo Tosatti on 12 Apr 2010 13:20
On Mon, Apr 12, 2010 at 04:02:24PM +0800, Xiao Guangrong wrote:
> - 'vcpu' is not used while mark parent unsync, so remove it
> - if it has alread marked unsync, no need to walk it's parent
>
> Signed-off-by: Xiao Guangrong <xiaoguangrong(a)cn.fujitsu.com>

Xiao,

Did you actually see this codepath as being performance sensitive?

I'd prefer to not touch it.

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From: Xiao Guangrong on 12 Apr 2010 22:00


Marcelo Tosatti wrote:

> Xiao,
>
> Did you actually see this codepath as being performance sensitive?

Actually, i not run benchmarks to contrast the performance before this patch
and after this patch.

>
> I'd prefer to not touch it.

This patch avoids walk all parents and i think this overload is really unnecessary.
It has other tricks in this codepath but i not noticed? :-)

Thanks,
Xiao
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From: Avi Kivity on 13 Apr 2010 08:00
On 04/13/2010 04:53 AM, Xiao Guangrong wrote:
>
>> I'd prefer to not touch it.
>>
> This patch avoids walk all parents and i think this overload is really unnecessary.
> It has other tricks in this codepath but i not noticed? :-)
>

There is also the advantage of code size reduction.

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error compiling committee.c: too many arguments to function

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