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Date: Fri, 17 May 2024 18:25:16 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.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 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.
Thanks,
Namhyung
>
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
> tools/perf/Documentation/perf-top.txt | 6 +++---
> tools/perf/builtin-top.c | 23 +++++++++++++----------
> tools/perf/ui/browsers/hists.c | 7 ++++---
> tools/perf/util/top.h | 2 +-
> 4 files changed, 21 insertions(+), 17 deletions(-)
>
> diff --git a/tools/perf/Documentation/perf-top.txt b/tools/perf/Documentation/perf-top.txt
> index 667e5102075e..f1524cc0d409 100644
> --- a/tools/perf/Documentation/perf-top.txt
> +++ b/tools/perf/Documentation/perf-top.txt
> @@ -124,9 +124,9 @@ Default is to monitor all CPUS.
> --verbose::
> Be more verbose (show counter open errors, etc).
>
> --z::
> ---zero::
> - Zero history across display updates.
> +-Z::
> +--decay::
> + Decay rather than zero history across display updates.
>
> -s::
> --sort::
> diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
> index e8cbbf10d361..8f06635cb7cd 100644
> --- a/tools/perf/builtin-top.c
> +++ b/tools/perf/builtin-top.c
> @@ -266,10 +266,10 @@ static void perf_top__show_details(struct perf_top *top)
> more = symbol__annotate_printf(&he->ms, top->sym_evsel);
>
> if (top->evlist->enabled) {
> - if (top->zero)
> - symbol__annotate_zero_histogram(symbol, top->sym_evsel->core.idx);
> - else
> + if (top->decay_samples)
> symbol__annotate_decay_histogram(symbol, top->sym_evsel->core.idx);
> + else
> + symbol__annotate_zero_histogram(symbol, top->sym_evsel->core.idx);
> }
> if (more != 0)
> printf("%d lines not displayed, maybe increase display entries [e]\n", more);
> @@ -292,11 +292,11 @@ static void perf_top__resort_hists(struct perf_top *t)
> hists__unlink(hists);
>
> if (evlist->enabled) {
> - if (t->zero) {
> - hists__delete_entries(hists);
> - } else {
> + if (t->decay_samples) {
> hists__decay_entries(hists, t->hide_user_symbols,
> t->hide_kernel_symbols);
> + } else {
> + hists__delete_entries(hists);
> }
> }
>
> @@ -460,7 +460,9 @@ static void perf_top__print_mapped_keys(struct perf_top *top)
> fprintf(stdout,
> "\t[U] hide user symbols. \t(%s)\n",
> top->hide_user_symbols ? "yes" : "no");
> - fprintf(stdout, "\t[z] toggle sample zeroing. \t(%d)\n", top->zero ? 1 : 0);
> + fprintf(stdout,
> + "\t[z] toggle sample zeroing/decaying. \t(%s)\n",
> + top->decay_samples ? "decay" : "zero");
> fprintf(stdout, "\t[qQ] quit.\n");
> }
>
> @@ -583,7 +585,7 @@ static bool perf_top__handle_keypress(struct perf_top *top, int c)
> top->hide_user_symbols = !top->hide_user_symbols;
> break;
> case 'z':
> - top->zero = !top->zero;
> + top->decay_samples = !top->decay_samples;
> break;
> default:
> break;
> @@ -648,7 +650,7 @@ static void *display_thread_tui(void *arg)
> ret = evlist__tui_browse_hists(top->evlist, help, &hbt, top->min_percent,
> &top->session->header.env, !top->record_opts.overwrite);
> if (ret == K_RELOAD) {
> - top->zero = true;
> + top->decay_samples = false;
> goto repeat;
> } else
> stop_top();
> @@ -1502,7 +1504,8 @@ int cmd_top(int argc, const char **argv)
> "child tasks do not inherit counters"),
> OPT_STRING(0, "sym-annotate", &top.sym_filter, "symbol name",
> "symbol to annotate"),
> - OPT_BOOLEAN('z', "zero", &top.zero, "zero history across updates"),
> + OPT_BOOLEAN('Z', "decay", &top.decay_samples,
> + "decay rather than zero history across updates"),
> OPT_CALLBACK('F', "freq", &top.record_opts, "freq or 'max'",
> "profile at this frequency",
> record__parse_freq),
> diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
> index b7219df51236..bcc4720f8198 100644
> --- a/tools/perf/ui/browsers/hists.c
> +++ b/tools/perf/ui/browsers/hists.c
> @@ -2305,8 +2305,8 @@ static int hists_browser__scnprintf_title(struct hist_browser *browser, char *bf
> " drop: %" PRIu64 "/%" PRIu64,
> top->drop, top->drop_total);
>
> - if (top->zero)
> - printed += scnprintf(bf + printed, size - printed, " [z]");
> + if (top->decay_samples)
> + printed += scnprintf(bf + printed, size - printed, " [decay]");
>
> perf_top__reset_sample_counters(top);
> }
> @@ -3209,9 +3209,10 @@ static int evsel__hists_browse(struct evsel *evsel, int nr_events, const char *h
> continue;
> case 'z':
> if (!is_report_browser(hbt)) {
> + /* Toggle between zeroing and decaying samples. */
> struct perf_top *top = hbt->arg;
>
> - top->zero = !top->zero;
> + top->decay_samples = !top->decay_samples;
> }
> continue;
> case 'L':
> diff --git a/tools/perf/util/top.h b/tools/perf/util/top.h
> index 4c5588dbb131..b2c199925b36 100644
> --- a/tools/perf/util/top.h
> +++ b/tools/perf/util/top.h
> @@ -32,7 +32,7 @@ struct perf_top {
> u64 guest_us_samples, guest_kernel_samples;
> int print_entries, count_filter, delay_secs;
> int max_stack;
> - bool hide_kernel_symbols, hide_user_symbols, zero;
> + bool hide_kernel_symbols, hide_user_symbols, decay_samples;
> #ifdef HAVE_SLANG_SUPPORT
> bool use_tui;
> #endif
> --
> 2.45.0.rc1.225.g2a3ae87e7f-goog
>
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