Re: [PATCH 0/4] perf ftrace: Add 'profile' subcommand (v1)

[Ian Rogers]

On Tue, Jul 30, 2024 at 12:19 PM Arnaldo Carvalho de Melo
<acme@xxxxxxxxxx> wrote:
>
> On Sun, Jul 28, 2024 at 05:41:23PM -0700, Namhyung Kim wrote:
> > Hello,
> >
> > This is an attempt to extend perf ftrace command to show a kernel function
> > profile using the function_graph tracer.  This is useful to see detailed
> > info like total, average, max time (in usec) and number of calls for each
> > function.
> >
> >   $ sudo perf ftrace profile -- sync | head
> >   # Total (us)   Avg (us)   Max (us)      Count   Function
> >       7638.372   7638.372   7638.372          1   __do_sys_sync
> >       7638.059   7638.059   7638.059          1   ksys_sync
> >       5893.959   1964.653   3747.963          3   iterate_supers
> >       5214.181    579.353   1688.752          9   schedule
> >       3585.773     44.269   3537.329         81   sync_inodes_one_sb
> >       3566.179     44.027   3537.078         81   sync_inodes_sb
> >       1976.901    247.113   1968.070          8   filemap_fdatawait_keep_errors
> >       1974.367    246.796   1967.895          8   __filemap_fdatawait_range
> >       1935.407     37.219   1157.627         52   folio_wait_writeback
> >
> > While the kernel also provides the similar functionality IIRC under
> > CONFIG_FUNCTION_PROFILER, it's often not enabled on disto kernels so I
> > implemented it in user space.
>
> Great functionality, tested it all and applied to tmp.perf-tools-next,
> will be in perf-tools-next after one last round of container builds.
>
> The discussion about libcap seems to still be open, so I'm applying what
> is in this series as it is small and simple, we can go on from there.

Sgtm. I did the libcap cleanup on perf-tools-next, but
tmp.perf-tools-next hasn't been merged there for 3 weeks. It'd be nice
to rebase the patch on perf-tools-next, but should I just shift to
working on tmp.perf-tools-next?

Thanks,
Ian

> Thanks!
>
> - Arnaldo
>
> > Also it can support function filters like 'perf ftrace trace' so users
> > can focus on some target functions and change the buffer size if needed.
> >
> >   $ sudo perf ftrace profile -h
> >
> >    Usage: perf ftrace [<options>] [<command>]
> >       or: perf ftrace [<options>] -- [<command>] [<options>]
> >       or: perf ftrace {trace|latency|profile} [<options>] [<command>]
> >       or: perf ftrace {trace|latency|profile} [<options>] -- [<command>] [<options>]
> >
> >       -a, --all-cpus        System-wide collection from all CPUs
> >       -C, --cpu <cpu>       List of cpus to monitor
> >       -G, --graph-funcs <func>
> >                             Trace given functions using function_graph tracer
> >       -g, --nograph-funcs <func>
> >                             Set nograph filter on given functions
> >       -m, --buffer-size <size>
> >                             Size of per cpu buffer, needs to use a B, K, M or G suffix.
> >       -N, --notrace-funcs <func>
> >                             Do not trace given functions
> >       -p, --pid <pid>       Trace on existing process id
> >       -s, --sort <key>      Sort result by key: total (default), avg, max, count, name.
> >       -T, --trace-funcs <func>
> >                             Trace given functions using function tracer
> >       -v, --verbose         Be more verbose
> >           --tid <tid>       Trace on existing thread id (exclusive to --pid)
> >
> >
> > The code is also available in 'perf/ftrace-profile-v1' branch at
> > git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git
> >
> > Thanks,
> > Namhyung
> >
> >
> > Namhyung Kim (4):
> >   perf ftrace: Add 'tail' option to --graph-opts
> >   perf ftrace: Factor out check_ftrace_capable()
> >   perf ftrace: Add 'profile' command
> >   perf ftrace: Add -s/--sort option to profile sub-command
> >
> >  tools/perf/Documentation/perf-ftrace.txt |  48 ++-
> >  tools/perf/builtin-ftrace.c              | 439 +++++++++++++++++++++--
> >  tools/perf/util/ftrace.h                 |   3 +
> >  3 files changed, 463 insertions(+), 27 deletions(-)
> >
> > --
> > 2.46.0.rc1.232.g9752f9e123-goog