Re: [PATCH v3 0/5] mm/memcg: Reduce kmemcache memory accounting overhead

Waiman Long
2021-04-15T17:41:14Z

On 4/15/21 1:10 PM, Matthew Wilcox wrote:
> On Tue, Apr 13, 2021 at 09:20:22PM -0400, Waiman Long wrote:
>> With memory accounting disable, the run time was 2.848s. With memory
>> accounting enabled, the run times with the application of various
>> patches in the patchset were:
>>
>> Applied patches Run time Accounting overhead Overhead %age
>> --------------- -------- ------------------- -------------
>> None 10.800s 7.952s 100.0%
>> 1-2 9.140s 6.292s 79.1%
>> 1-3 7.641s 4.793s 60.3%
>> 1-5 6.801s 3.953s 49.7%
> I think this is a misleading way to report the overhead. I would have said:
>
> 10.800s 7.952s 279.2%
> 9.140s 6.292s 220.9%
> 7.641s 4.793s 168.3%
> 6.801s 3.953s 138.8%
>
What I want to emphasize is the reduction in the accounting overhead
part of execution time. Your percentage used the accounting disable time
as the denominator. I think both are valid, I will be more clear about
that in my version of the patch.

Thanks,
Longman