On 2020/2/14 20:28, Dr. David Alan Gilbert wrote:
> * Keqian Zhu (zhukeqi...@huawei.com) wrote:
>> At the tail stage of throttle, VM is very sensitive to
>> CPU percentage. We just throttle 30% of remaining CPU
>> when throttle is more than 80 percentage.
>
> This is a bit unusual; all of the rest of the throttling has no
> fixed constants; all values are set by parameters.
>
> You've got the two, the '80' and the '0.3'
>
> I thinkt he easy solution is to replace your parameter 'tailslow' by two
> new parameters; 'tailstart' and 'tailrate'; both defaulting to 100%.
>
> Then you make it:
>
> if (cpu_throttle_now >= pct_tailstart) {
> /* Eat some scale of CPU from remaining */
> cpu_throttle_inc = ceil((100 - cpu_throttle_now) * pct_tailrate);
>
> (with percentage scaling added).
>
> Then setting 'tailstart' to 80 and 'tailrate' to 30 is equivalent to
> what you have, but means we have no magical constants in the code.
>
Yes, this is a good suggestion. Though this patch is not the final idea,
I will apply it when throttle approach is decided.
> Dave
>
>
[...]
>> --
>> 2.19.1
>>
> --
> Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
>
>
> .
>
Thanks,
Keqian
