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

[Arnaldo Carvalho de Melo]

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.

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