Re: [PATCH v2 2/4] percpu_stats: Enable 64-bit counts in 32-bit architectures

Waiman Long
2016-04-12T18:15:34Z

On 04/11/2016 06:17 PM, Tejun Heo wrote:
> Hello, Waiman.
>
> On Fri, Apr 08, 2016 at 02:45:38PM -0400, Waiman Long wrote:
>> The percpu_stats construct allows minimal overhead in maintaining statistics
>> counts. The percpu_counter construct, on the other hand, has a higher
>> performance overhead and a bit more complex to set up and tear down when
> If you're referring to the preemption on/off, as I wrote before, we'll
> probably be able to improve that with this_cpu_add_return so that the
> only extra overhead is an easily predictable branch which is extremely
> cheap. It's better to improve common constructs anyway.
>
>> more than one statistics counts are needed. In fact, my first draft of the
> And yeah, it can be cumbersome to set up and tear down multiple
> percpu_counters. If there are enough consumers, we can extend
> percpu_counter to handle multiple counters, right?
>
> Thanks.
>

I have updated my patch to use percpu_counter instead. Thanks for all
the comments and review so far.

Cheers,
Longman