linux-kernel - Re: [RFC/PATCH] perf lock contention: Add -J/--inject-delay option

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Message-ID: <aB0MSvrGA5fgH5Hj@x1>
Date: Thu, 8 May 2025 16:55:54 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Namhyung Kim <namhyung@...nel.org>
Cc: 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, Stephane Eranian <eranian@...gle.com>
Subject: Re: [RFC/PATCH] perf lock contention: Add -J/--inject-delay option

On Thu, May 08, 2025 at 10:30:02AM -0700, Namhyung Kim wrote:
> On Thu, May 08, 2025 at 11:45:58AM -0300, Arnaldo Carvalho de Melo wrote:
> > On Mon, Feb 24, 2025 at 11:59:29PM -0800, Namhyung Kim wrote:
> > > This is to slow down lock acquistion (on contention locks) deliberately.
> > > A possible use case is to estimate impact on application performance by
> > > optimization of kernel locking behavior.  By delaying the lock it can
> > > simulate the worse condition as a control group, and then compare with
> > > the current behavior as a optimized condition.

> > So this looks useful, I guess we can proceed and merge it?

> That'd be great. :)

Can you please refresh it?

⬢ [acme@...lbox perf-tools-next]$        git am ./20250224_namhyung_perf_lock_contention_add_j_inject_delay_option.mbx
Applying: perf lock contention: Add -J/--inject-delay option
error: patch failed: tools/perf/util/bpf_skel/lock_contention.bpf.c:11
error: tools/perf/util/bpf_skel/lock_contention.bpf.c: patch does not apply
error: patch failed: tools/perf/util/lock-contention.h:140
error: tools/perf/util/lock-contention.h: patch does not apply
Patch failed at 0001 perf lock contention: Add -J/--inject-delay option
hint: Use 'git am --show-current-patch=diff' to see the failed patch
hint: When you have resolved this problem, run "git am --continue".
hint: If you prefer to skip this patch, run "git am --skip" instead.
hint: To restore the original branch and stop patching, run "git am --abort".
hint: Disable this message with "git config set advice.mergeConflict false"
⬢ [acme@...lbox perf-tools-next]$ git am --abort
⬢ [acme@...lbox perf-tools-next]$ 
⬢ [acme@...lbox perf-tools-next]$ patch -p1 < ./20250224_namhyung_perf_lock_contention_add_j_inject_delay_option.mbx
patching file tools/perf/Documentation/perf-lock.txt
Hunk #1 succeeded at 216 (offset 1 line).
patching file tools/perf/builtin-lock.c
Hunk #2 succeeded at 2003 (offset 30 lines).
Hunk #3 succeeded at 2508 (offset 30 lines).
Hunk #4 succeeded at 2652 (offset 30 lines).
patching file tools/perf/util/bpf_lock_contention.c
Hunk #1 succeeded at 261 (offset 78 lines).
Hunk #2 succeeded at 373 (offset 80 lines).
patching file tools/perf/util/bpf_skel/lock_contention.bpf.c
Hunk #1 succeeded at 14 with fuzz 2 (offset 3 lines).
Hunk #2 succeeded at 152 (offset 35 lines).
Hunk #3 FAILED at 153.
Hunk #4 succeeded at 397 (offset 39 lines).
Hunk #5 succeeded at 835 with fuzz 1 (offset 230 lines).
1 out of 5 hunks FAILED -- saving rejects to file tools/perf/util/bpf_skel/lock_contention.bpf.c.rej
patching file tools/perf/util/lock-contention.h
Hunk #2 succeeded at 146 with fuzz 1.
Hunk #3 succeeded at 156 (offset 1 line).
⬢ [acme@...lbox perf-tools-next]$