Re: [PATCH 2/3] bcache: Convert to lib/time_stats

From: Coly Li
Date: Wed Aug 31 2022 - 22:20:16 EST




> 2022年9月1日 01:36,Kent Overstreet <kent.overstreet@xxxxxxxxx> 写道:
>
> On Thu, Sep 01, 2022 at 01:02:37AM +0800, Coly Li wrote:
>> Can I understand that rate = 1/frequency ? Then frequency 4 is around to rate 0.
>
> Correct, rate = 1/frequency.
>
>>> The quantiles are for the duration, they give you an idea of the statistical
>>> distribution, see https://en.wikipedia.org/wiki/Quantile
>>
>> I wanted to ask how to read the quantiles line. Does it mean that 1 ns is
>> equally divided by 15 segments, and the counter values are for the divided
>> 1/15 ns segments?
>
> It is the 15 boundaries between 16 equal segments, yes.
>
>> Quantiles are much humane, standard deviation is scared… Just FYI LOL.
>
> That's valuable feedback then, maybe we'll keep both. The more expensive part of
> time stats is just ingesting data points, but we've got a percpu buffer frontend
> for that - just doing a bit more moth doesn't cost much.

I don’t have more question so far. Thanks for the detailed replay.

Coly Li