From: Steven Rostedt <rostedt@goodmis.org>
To: Namhyung Kim <namhyung@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Tom Zanussi <zanussi@kernel.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
"Daniel Bristot de Oliveira Subject: [PATCH] tracing:"
<bristot@redhat.com>
Subject: Re: [PATCH v2] tracing: Add linear buckets to histogram logic
Date: Tue, 6 Jul 2021 20:50:39 -0400 [thread overview]
Message-ID: <20210706205039.64182493@rorschach.local.home> (raw)
In-Reply-To: <CAM9d7chmHmm3tjJik5EQDOJOdn7G0D3W9EJUogf_POnyTe6tcA@mail.gmail.com>
On Tue, 6 Jul 2021 16:20:07 -0700
Namhyung Kim <namhyung@kernel.org> wrote:
> > { bytes_req: ~ 1400-1499 } hitcount: 30
> > { bytes_req: ~ 2000-2099 } hitcount: 6
> > { bytes_req: ~ 4000-4099 } hitcount: 2168
> > { bytes_req: ~ 5000-5099 } hitcount: 6
>
> For consistency with the log2 histogram, I'd like to see
>
> { bytes_req: ~ 100 } hitcount: 3149
> { bytes_req: ~ 200 } hitcount: 1468
> { bytes_req: ~ 300 } hitcount: 39
> ...
>
> Or, if you really care about the value range
>
> { bytes_req: 0 ~ 99 } hitcount: 3149
> { bytes_req: 100 ~ 199 } hitcount: 1468
> { bytes_req: 200 ~ 299 } hitcount: 39
(Let the bike-shedding begin! ;-)
I actually dislike the log2 notation. For example, I just ran it with
this:
># echo 'hist:keys=bytes_req.log2:sort=bytes_req' > events/kmem/kmalloc/trigger
># cat events/kmem/kmalloc/hist
# event histogram
#
# trigger info: hist:keys=bytes_req.log2:vals=hitcount:sort=bytes_req.log2:size=2048 [active]
#
{ bytes_req: ~ 2^5 } hitcount: 8
{ bytes_req: ~ 2^6 } hitcount: 2
{ bytes_req: ~ 2^7 } hitcount: 4
{ bytes_req: ~ 2^8 } hitcount: 2
{ bytes_req: ~ 2^9 } hitcount: 2
{ bytes_req: ~ 2^10 } hitcount: 3
Totals:
Hits: 21
Entries: 6
Dropped: 0
And I don't know if that first entry is: 2^4 - 2^5 or if it is 2^5 - 2^6.
And to me '~' means "approximately", but I also took it as "not exactly".
I used it as:
{ bytes_req: ~ 1400-1499 } hitcount: 30
To mean, it's "approximately somewhere between 1400 and 1499" so, I kept the "~".
Now for your suggestions:
> { bytes_req: ~ 100 } hitcount: 3149
> { bytes_req: ~ 200 } hitcount: 1468
> { bytes_req: ~ 300 } hitcount: 39
Suffers the same fate as I dislike in log2. Is " ~ 100" 0-100 or 100-200?
> { bytes_req: 0 ~ 99 } hitcount: 3149
> { bytes_req: 100 ~ 199 } hitcount: 1468
> { bytes_req: 200 ~ 299 } hitcount: 39
I feel is farther from log2 than my version. Stating that "~" means
approximation, what does "0 ~ 99" really mean?
So far I prefer my original version.
BTW, we are also working on a user space parser for this, thus the
output format of all hist logic is going to be a user space API (if it
hasn't already become one.)
So we do need to get this correct for the long haul.
-- Steve
next prev parent reply other threads:[~2021-07-07 0:50 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20210706154315.3567166e@gandalf.local.home>
2021-07-06 22:09 ` [PATCH v2] tracing: Add linear buckets to histogram logic Tom Zanussi
2021-07-07 0:35 ` Steven Rostedt
2021-07-06 23:20 ` Namhyung Kim
2021-07-07 0:50 ` Steven Rostedt [this message]
2021-07-07 14:00 ` Namhyung Kim
2021-07-07 15:11 ` Steven Rostedt
2021-07-07 15:18 ` Tom Zanussi
[not found] ` <20210707195851.ae0aa69f0d37ed6d91c68e06@kernel.org>
2021-07-07 13:44 ` Steven Rostedt
2021-07-07 18:26 ` Steven Rostedt
2021-07-07 18:28 ` Steven Rostedt
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