Messages in this thread | | | From | Namhyung Kim <> | Subject | Re: [PATCH 10/11] perf tool: give user better message if precise is not supported | Date | Sat, 21 Jul 2012 19:40:33 +0900 |
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Hi, David
On Fri, 20 Jul 2012 17:25:55 -0600, David Ahern wrote: > If the PEBS is not supported (e.g., a VM) and the precise modifier is > set the user is given a confusing error message: > > $ perf top -e cycles:p > > The sys_perf_event_open() syscall returned with 95 (Operation not supported). > /bin/dmesg may provide additional information. > No CONFIG_PERF_EVENTS=y kernel support configured? > > $ 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. > > Fatal: No hardware sampling interrupt available. No APIC? If so then you can > boot the kernel with the "lapic" boot parameter to force-enable it. > > Which in no way conveys the real error. With this patch: > $ perf top -e cycles:p > PEBS request not supported. Try removing 'p' modifier > > $ perf record -e cycles:p -a -- sleep 1 > PEBS request not supported. Try removing 'p' modifier >
The name 'PEBS' is intel-specific, so shouldn't we try to avoid using it directly? How about this:
Precise event sampling is not supported. Try removing 'p' modifier
Thanks, Namhyung
> Signed-off-by: David Ahern <dsahern@gmail.com> > Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net> > Cc: Ingo Molnar <mingo@kernel.org> > Cc: Jiri Olsa <jolsa@redhat.com> > Cc: Namhyung Kim <namhyung@kernel.org> > Cc: Frederic Weisbecker <fweisbec@gmail.com> > Cc: Peter Zijlstra <peterz@infradead.org> > --- > tools/perf/builtin-record.c | 4 ++++ > tools/perf/builtin-top.c | 4 ++++ > 2 files changed, 8 insertions(+) > > diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c > index f5a6452..911e300 100644 > --- a/tools/perf/builtin-record.c > +++ b/tools/perf/builtin-record.c > @@ -267,6 +267,10 @@ try_again: > ui__error("The %s event is not supported.\n", > perf_evsel__name(pos)); > exit(EXIT_FAILURE); > + } else if ((err == ENOTSUP) && (attr->precise_ip)) { > + ui__error("PEBS request not supported. " > + "Try removing 'p' modifier\n"); > + exit(EXIT_FAILURE); > } > > printf("\n"); > diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c > index 0ce665c..1706dc9 100644 > --- a/tools/perf/builtin-top.c > +++ b/tools/perf/builtin-top.c > @@ -968,6 +968,10 @@ try_again: > ui__error("Too many events are opened.\n" > "Try again after reducing the number of events\n"); > goto out_err; > + } else if ((err == ENOTSUP) && (attr->precise_ip)) { > + ui__error("PEBS request not supported. " > + "Try removing 'p' modifier\n"); > + goto out_err; > } > > ui__error("The sys_perf_event_open() syscall "
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