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SubjectRe: [PATCH 1/1] perf:Adding --list-opts to usage string
Em Wed, Oct 14, 2015 at 10:29:05AM +0800, Yunlong Song escreveu:
> On 2015/10/13 23:24, Ramkumar Ramachandra wrote:
> > Arnaldo Carvalho de Melo wrote:
> >> Em Thu, Oct 08, 2015 at 10:59:50AM +0530, Sriram Raghunathan escreveu:
> >>> Minor change, adding --list-opts to usage string. So that it is
> >>> visible to the user on running perf --help. or just perf
> >>> from command line.
> >>
> >> Ramkumar, Yunlong, are you ok with this?

> > Not sure I understand the motivation, but I suppose it can't hurt to
> > show this detail?

> Agree with Ramkumar, --list-opts is redundant due to the existing [OPTIONS] in
> the perf_usage_string[].

I see, thinking about it now, it seems that this is because 'perf -h'
behaves differently from other tools, i.e.:

$ perf -h

usage: perf [--version] [--help] [OPTIONS] COMMAND [ARGS]

The most commonly used perf commands are:
annotate Read perf.data (created by perf record) and display annotated code
archive Create archive with object files with build-ids found in perf.data file
bench General framework for benchmark suites
buildid-cache Manage build-id cache.
buildid-list List the buildids in a perf.data file
<SNIP>
test Runs sanity tests.
timechart Tool to visualize total system behavior during a workload
top System profiling tool.
trace strace inspired tool
probe Define new dynamic tracepoints

See 'perf help COMMAND' for more information on a specific command.

--------------------------

While:

$ perf stat -h

usage: perf stat [<options>] [<command>]

-T, --transaction hardware transaction statistics
-e, --event <event> event selector. use 'perf list' to list available events
--filter <filter>
event filter
-i, --no-inherit child tasks do not inherit counters
-p, --pid <pid> stat events on existing process id
-t, --tid <tid> stat events on existing thread id
-a, --all-cpus system-wide collection from all CPUs
<SNIP>
-I, --interval-print <n>
print counts at regular interval in ms (>= 10)
--per-socket aggregate counts per processor socket
--per-core aggregate counts per physical processor core
--per-thread aggregate counts per thread
-D, --delay <n> ms to wait before starting measurement after program start

--------------------------

One doesn't show what options can be used, the other does, so there is
an inconsistency, this and the fact that 'perf -h' outputs to stdout,
'perf stat -h' and the other builtins output to stderr. I think all
should output to stdout, just like 'ls --help', what do you think?

- Arnaldo

> >>>
> >>> const char perf_usage_string[] =
> >>> - "perf [--version] [--help] [OPTIONS] COMMAND [ARGS]";
> >>> + "perf [--version] [--help] [--list-opts] [OPTIONS] COMMAND [ARGS]";
>
> --
> Thanks,
> Yunlong Song


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