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

[Ian Rogers]

On Sun, Jul 28, 2024 at 5:41 PM Namhyung Kim <namhyung@xxxxxxxxxx> 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.
>
> 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

Lgtm, need to think about (rebase, etc) wrt the libcap change I sent
but otherwise:
Reviewed-by: Ian Rogers <irogers@xxxxxxxxxx>

Thanks,
Ian

> 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
>