Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Content-Type: text/plain;
        charset=utf-8
Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3696.120.41.1.1\))
Subject: Re: [PATCH 2/3] bcache: Convert to lib/time_stats
From:   Coly Li <colyli@suse.de>
In-Reply-To: <20220831173639.sb6bhg5xvn4gbkiu@moria.home.lan>
Date:   Thu, 1 Sep 2022 10:19:59 +0800
Cc:     linux-kernel@vger.kernel.org, linux-bcache@vger.kernel.org
Content-Transfer-Encoding: quoted-printable
Message-Id: <20DDF7B2-8433-49EE-8F9F-CB335D2E7B6C@suse.de>
References: <20220829165344.2958640-1-kent.overstreet@linux.dev>
 <20220829165344.2958640-3-kent.overstreet@linux.dev>
 <14ACCED7-D24D-4AC4-8677-F7F4630A840A@suse.de>
 <20220831165437.l27raas6k5nlqsdg@moria.home.lan>
 <1F91055C-4253-42CD-8A4A-8B8EA2CF1D6E@suse.de>
 <20220831173639.sb6bhg5xvn4gbkiu@moria.home.lan>
To:     Kent Overstreet <kent.overstreet@linux.dev>
Precedence: bulk


> 2022=E5=B9=B49=E6=9C=881=E6=97=A5 01:36=EF=BC=8CKent Overstreet =
<kent.overstreet@linux.dev> =E5=86=99=E9=81=93=EF=BC=9A
>=20
> On Thu, Sep 01, 2022 at 01:02:37AM +0800, Coly Li wrote:
>> Can I understand that rate =3D 1/frequency ?  Then frequency 4 is =
around to rate 0.
>=20
> Correct, rate =3D 1/frequency.
>=20
>>> The quantiles are for the duration, they give you an idea of the =
statistical
>>> distribution, see https://en.wikipedia.org/wiki/Quantile
>>=20
>> 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?
>=20
> It is the 15 boundaries between 16 equal segments, yes.
>=20
>> Quantiles are much humane, standard deviation is scared=E2=80=A6 Just =
FYI LOL.
>=20
> 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=E2=80=99t have more question so far. Thanks for the detailed =
replay.

Coly Li=