linux-kernel - Re: [PATCH 2/3] bcache: Convert to lib/time

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Date:   Thu, 1 Sep 2022 10:19:59 +0800
From:   Coly Li <colyli@...e.de>
To:     Kent Overstreet <kent.overstreet@...ux.dev>
Cc:     linux-kernel@...r.kernel.org, linux-bcache@...r.kernel.org
Subject: Re: [PATCH 2/3] bcache: Convert to lib/time_stats



> 2022年9月1日 01:36，Kent Overstreet <kent.overstreet@...ux.dev> 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