linux-kernel - Re: [PATCH v1] perf top: Make zeroing histogram on refresh the default

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Date: Tue, 21 May 2024 16:45:55 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Ingo Molnar <mingo@...nel.org>, Namhyung Kim <namhyung@...nel.org>
Cc: Ian Rogers <irogers@...gle.com>, Peter Zijlstra <peterz@...radead.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Kan Liang <kan.liang@...ux.intel.com>,
	Changbin Du <changbin.du@...wei.com>,
	John Fastabend <john.fastabend@...il.com>,
	Andrii Nakryiko <andrii@...nel.org>,
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
	Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH v1] perf top: Make zeroing histogram on refresh the
 default

On Fri, May 17, 2024 at 06:25:16PM -0700, Namhyung Kim wrote:
> On Thu, May 16, 2024 at 3:22 PM Ian Rogers <irogers@...gle.com> wrote:
> > Instead of decaying histograms over time change it so that they are
> > zero-ed on each perf top refresh. Previously the option '-z', or
> > pressing 'z' in tui mode, would enable this behavior. Decaying samples
> > is non-intuitive as it isn't how "top" works. Make zeroing on refresh
> > the default and rename the command line options from 'z' to 'Z' and
> > 'zero' to 'decay'.
 
> While it may make more sense, I'm afraid of changing the default
> behavior.  I think we can add a config option for this.
 
> Also instead of adding a new option, it should be able to use the
> existing --no-zero option.

Hi Ingo,

	What do you think? -z and the default to decaying is in 'perf
top' since the very beginning, when it was called kerneltop:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e0143bad9dbf2a8fad4c5430562bceba196b66ea

Cheers,

- Arnaldo