perf test: Allow running just a subset of the available tests

To obtain a list of available tests:

[root@emilia linux]# perf test list
 1: vmlinux symtab matches kallsyms
 2: detect open syscall event
 3: detect open syscall event on all cpus
 4: read samples using the mmap interface
 5: parse events tests
[root@emilia linux]#

To list just a subset:

[root@emilia linux]# perf test list syscall
 2: detect open syscall event
 3: detect open syscall event on all cpus
[root@emilia linux]#

To run a subset:

[root@emilia linux]# perf test detect
 2: detect open syscall event: Ok
 3: detect open syscall event on all cpus: Ok
[root@emilia linux]#

Specific tests can be chosen by number:

[root@emilia linux]# perf test 1 3 parse
 1: vmlinux symtab matches kallsyms: Ok
 3: detect open syscall event on all cpus: Ok
 5: parse events tests: Ok
[root@emilia linux]#

Now to write more tests!

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-nqec2145qfxdgimux28aw7v8@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/Documentation/perf-test.txt b/tools/perf/Documentation/perf-test.txt
index 2c3b462..b24ac40 100644
--- a/tools/perf/Documentation/perf-test.txt
+++ b/tools/perf/Documentation/perf-test.txt
@@ -8,13 +8,19 @@
 SYNOPSIS
 --------
 [verse]
-'perf test <options>'
+'perf test [<options>] [{list <test-name-fragment>|[<test-name-fragments>|<test-numbers>]}]'
 
 DESCRIPTION
 -----------
 This command does assorted sanity tests, initially through linked routines but
 also will look for a directory with more tests in the form of scripts.
 
+To get a list of available tests use 'perf test list', specifying a test name
+fragment will show all tests that have it.
+
+To run just specific tests, inform test name fragments or the numbers obtained
+from 'perf test list'.
+
 OPTIONS
 -------
 -v::