linux-kernel - Re: [PATCH v4 1/2] perf trace: Implement syscall summary in BPF

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Message-ID: <aAkUyFjRFLkS170u@x1>
Date: Wed, 23 Apr 2025 13:26:48 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Howard Chu <howardchu95@...il.com>
Cc: Namhyung Kim <namhyung@...nel.org>, Ian Rogers <irogers@...gle.com>,
	Kan Liang <kan.liang@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
	linux-perf-users@...r.kernel.org, Song Liu <song@...nel.org>,
	bpf@...r.kernel.org
Subject: Re: [PATCH v4 1/2] perf trace: Implement syscall summary in BPF

On Fri, Mar 28, 2025 at 06:46:36PM -0700, Howard Chu wrote:
> Hello Namhyung,
> 
> On Tue, Mar 25, 2025 at 9:40 PM Namhyung Kim <namhyung@...nel.org> wrote:
> >
> > When -s/--summary option is used, it doesn't need (augmented) arguments
> > of syscalls.  Let's skip the augmentation and load another small BPF
> > program to collect the statistics in the kernel instead of copying the
> > data to the ring-buffer to calculate the stats in userspace.  This will
> > be much more light-weight than the existing approach and remove any lost
> > events.
> >
> > Let's add a new option --bpf-summary to control this behavior.  I cannot
> > make it default because there's no way to get e_machine in the BPF which
> > is needed for detecting different ABIs like 32-bit compat mode.
> >
> > No functional changes intended except for no more LOST events. :)
> >
> >   $ sudo ./perf trace -as --summary-mode=total --bpf-summary sleep 1
> >
> >    Summary of events:
> >
> >    total, 6194 events
> >
> >      syscall            calls  errors  total       min       avg       max       stddev
> >                                        (msec)    (msec)    (msec)    (msec)        (%)
> >      --------------- --------  ------ -------- --------- --------- ---------     ------
> >      epoll_wait           561      0  4530.843     0.000     8.076   520.941     18.75%
> >      futex                693     45  4317.231     0.000     6.230   500.077     21.98%
> >      poll                 300      0  1040.109     0.000     3.467   120.928     17.02%
> >      clock_nanosleep        1      0  1000.172  1000.172  1000.172  1000.172      0.00%
> >      ppoll                360      0   872.386     0.001     2.423   253.275     41.91%
> >      epoll_pwait           14      0   384.349     0.001    27.453   380.002     98.79%
> >      pselect6              14      0   108.130     7.198     7.724     8.206      0.85%
> >      nanosleep             39      0    43.378     0.069     1.112    10.084     44.23%
> >      ...

I added the following to align sched_[gs]etaffinity,

Thanks,

- Arnaldo


diff --git a/tools/perf/util/bpf-trace-summary.c b/tools/perf/util/bpf-trace-summary.c
index 114d8d9ed9b2d3f3..af37d3bb5f9c42e7 100644
--- a/tools/perf/util/bpf-trace-summary.c
+++ b/tools/perf/util/bpf-trace-summary.c
@@ -139,9 +139,9 @@ static int print_common_stats(struct syscall_data *data, FILE *fp)
 		/* TODO: support other ABIs */
 		name = syscalltbl__name(EM_HOST, node->syscall_nr);
 		if (name)
-			printed += fprintf(fp, "   %-15s", name);
+			printed += fprintf(fp, "   %-17s", name);
 		else
-			printed += fprintf(fp, "   syscall:%-7d", node->syscall_nr);
+			printed += fprintf(fp, "   syscall:%-9d", node->syscall_nr);
 
 		printed += fprintf(fp, " %8u %6u %9.3f %9.3f %9.3f %9.3f %9.2f%%\n",
 				   stat->count, stat->error, total, min, avg, max,