From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751793Ab2GUKkn (ORCPT ); Sat, 21 Jul 2012 06:40:43 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:59232 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751431Ab2GUKkl (ORCPT ); Sat, 21 Jul 2012 06:40:41 -0400 From: Namhyung Kim To: David Ahern Cc: acme@ghostprotocols.net, linux-kernel@vger.kernel.org, Ingo Molnar , Jiri Olsa , Frederic Weisbecker , Peter Zijlstra Subject: Re: [PATCH 10/11] perf tool: give user better message if precise is not supported References: <1342826756-64663-1-git-send-email-dsahern@gmail.com> <1342826756-64663-11-git-send-email-dsahern@gmail.com> Date: Sat, 21 Jul 2012 19:40:33 +0900 In-Reply-To: <1342826756-64663-11-git-send-email-dsahern@gmail.com> (David Ahern's message of "Fri, 20 Jul 2012 17:25:55 -0600") Message-ID: <87y5mdqtwe.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > Cc: Arnaldo Carvalho de Melo > Cc: Ingo Molnar > Cc: Jiri Olsa > Cc: Namhyung Kim > Cc: Frederic Weisbecker > Cc: Peter Zijlstra > --- > 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 "