linux-kernel - Re: RFE: perf lock contention --bpf on an RT kernel

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Date:   Thu, 17 Aug 2023 11:17:55 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        Ian Rogers <irogers@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Clark Williams <williams@...hat.com>,
        Michael Petlan <mpetlan@...hat.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: RFE: perf lock contention --bpf on an RT kernel

Em Thu, Aug 17, 2023 at 10:57:25AM -0300, Arnaldo Carvalho de Melo escreveu:
> Hi Namhyung, I noticed this when trying to use the BPF mode of perf lock
> contention on an RT kernel:
> 
> 
> I tried up to now the following patch, it loads, but produces no output
> :-\

To check that a BPF skel based programs works with this kernel I tried:

[root@...e perf-tools-next]# uname -a
Linux nine 5.14.0-284.18.1.rt14.303.el9_2.x86_64 #1 SMP PREEMPT_RT Wed May 31 13:18:55 EDT 2023 x86_64 x86_64 x86_64 GNU/Linux
[root@...e perf-tools-next]# tools/bpf/runqslower/.output/runqslower 50 | head -20
Tracing run queue latency higher than 50 us
TIME     COMM             PID           LAT(us)
11:13:47 ktimers/5        60                 54
11:13:47 irq_work/5       62                124
11:13:47 ktimers/5        60                 53
11:13:47 irq_work/5       62                 88
11:13:47 swapper/0        3942               59
11:13:47 ktimers/4        52                 55
11:13:47 irq_work/4       54                102
11:13:47 swapper/0        3942               51
11:13:47 ktimers/5        60                 54
11:13:47 irq_work/5       62                 93
11:13:47 swapper/0        3942               51
11:13:47 kworker/2:2      38                141
11:13:47 swapper/4        14                 90
11:13:47 swapper/6        642               102
11:13:47 swapper/7        77                 52
11:13:47 ktimers/7        76                103
11:13:47 irq_work/7       78                 92
11:13:47 ktimers/6        68                 83
[root@...e perf-tools-next]#

- Arnaldo