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perf tools: Give user better message if precise is not supported 

Platforms (e.g., VM's) without support for precise mode get a confusing
error message. e.g.,
$ perf record -e cycles:p -a -- sleep 1

  Error: sys_perf_event_open() syscall returned with 95 (Operation not
  supported).  /bin/dmesg may provide additional information.

  No hardware sampling interrupt available. No APIC? If so then you can
  boot the kernel with the "lapic" boot parameter to force-enable it.
  sleep: Terminated

which is not clear that precise mode might be the root problem. With this
patch:

$ perf record -e cycles:p -fo /tmp/perf.data -- sleep 1
  Error:
  'precise' request may not be supported. Try removing 'p' modifier
  sleep: Terminated

v2: softened message to 'may not be' supported per Robert's suggestion

Signed-off-by: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Richter <robert.richter@amd.com>
Link: http://lkml.kernel.org/r/1347569955-54626-4-git-send-email-dsahern@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
David Ahern 2012-09-13 14:59:15 -06:00 committed by Arnaldo Carvalho de Melo
parent 03f2f93ae0
commit 2305c82fb3
2 changed files with 9 additions and 0 deletions
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5
tools/perf/builtin-record.c
View File

@ -317,6 +317,11 @@ static int perf_record__open(struct perf_record *rec)
perf_evsel__name(pos));
rc = -err;
goto out;
} else if ((err == EOPNOTSUPP) && (attr->precise_ip)) {
ui__error("\'precise\' request may not be supported. "
"Try removing 'p' modifier\n");
rc = -err;
goto out;
}
printf("\n");

4
tools/perf/builtin-top.c
View File

@ -977,6 +977,10 @@ static void perf_top__start_counters(struct perf_top *top)
ui__error("Too many events are opened.\n"
"Try again after reducing the number of events\n");
goto out_err;
} else if ((err == EOPNOTSUPP) && (attr->precise_ip)) {
ui__error("\'precise\' request may not be supported. "
"Try removing 'p' modifier\n");
goto out_err;
}
ui__error("The sys_perf_event_open() syscall "