linux-kernel - Re: [PATCH] perf tools: Do not show trace command if it's not compiled in

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Date:	Tue, 12 Jan 2016 12:23:41 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Jiri Olsa <jolsa@...nel.org>
Cc:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	lkml <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH] perf tools: Do not show trace command if it's not
 compiled in

* Jiri Olsa <jolsa@...nel.org> wrote:

> The trace command still appears in help message when you
> run simple 'perf' command.
> 
> It's because the generate-cmdlist.sh does not care about the
> HAVE_LIBAUDIT_SUPPORT dependency of trace command and puts
> it into generated common_cmds array.
> 
> Wrapping trace command under HAVE_LIBAUDIT_SUPPORT dependency,
> which will exclude it from common_cmds array if HAVE_LIBAUDIT_SUPPORT
> is not set.

Btw., would it make sense to still list them, but denote them as '[NOT BUILT IN]':

 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
   config          Get and set variables in a configuration file.
   data            Data file related processing
   diff            Read perf.data files and display the differential profile
   evlist          List the event names in a perf.data file
   inject          Filter to augment the events stream with additional information
   kmem            Tool to trace/measure kernel memory properties
   kvm             Tool to trace/measure kvm guest os
   list            List all symbolic event types
   lock            Analyze lock events
   mem             Profile memory accesses
   record          Run a command and record its profile into perf.data
   report          Read perf.data (created by perf record) and display the profile
   sched           Tool to trace/measure scheduler properties (latencies)
   script          Read perf.data (created by perf record) and display trace output
   stat            Run a command and gather performance counter statistics
   test            Runs sanity tests.
   timechart       Tool to visualize total system behavior during a workload
   top             System profiling tool.
   probe           Define new dynamic tracepoints
   trace           [NOT BUILT IN] strace inspired tool

?

... and print something informative if someone tries to use it:

  triton:~/tip> perf trace
  Error: The 'trace' subcommand is not built into this version of perf.
  Solution: You can enable it by rebuilding perf with all required libraries installed.

Instead of the rather misleading:

  triton:~/tip> perf trace
  perf: 'trace' is not a perf-command. See 'perf --help'.

(Plus once we grow a 'perf upgrade' command, we can suggest rebuilding via that 
route.)

Thanks,

	Ingo