perf record: Disallow -c and -F option at the same time

It's confusing which one is effective when the both options are given.
The current code happens to use -c in this case but users might not be
aware of it.  We can change it to complain about that instead of relying
on the implicit priority.

Before:

  $ perf record -c 111111 -F 99 true
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.031 MB perf.data (8 samples) ]

  $ perf evlist -F
  cycles: sample_period=111111
  $

After:
  $ perf record -c 111111 -F 99 true
  cannot set frequency and period at the same time
  $

So this change can break existing usages, but I think it's rare to have
both options and it'd be better changing them.

Suggested-by: Alexey Alexandrov <aalexand@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20210402094020.28164-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/record.c b/tools/perf/util/record.c
index f99852d..43e5b56 100644 (file)
--- a/tools/perf/util/record.c
+++ b/tools/perf/util/record.c
@@ -157,9 +157,15 @@ static int get_max_rate(unsigned int *rate)
 static int record_opts__config_freq(struct record_opts *opts)
 {
        bool user_freq = opts->user_freq != UINT_MAX;
+       bool user_interval = opts->user_interval != ULLONG_MAX;
        unsigned int max_rate;
 
-       if (opts->user_interval != ULLONG_MAX)
+       if (user_interval && user_freq) {
+               pr_err("cannot set frequency and period at the same time\n");
+               return -1;
+       }
+
+       if (user_interval)
                opts->default_interval = opts->user_interval;
        if (user_freq)
                opts->freq = opts->user_freq;