From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754392AbbJUSEQ (ORCPT ); Wed, 21 Oct 2015 14:04:16 -0400 Received: from mail.kernel.org ([198.145.29.136]:45413 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753264AbbJUSEO (ORCPT ); Wed, 21 Oct 2015 14:04:14 -0400 Date: Wed, 21 Oct 2015 15:04:10 -0300 From: Arnaldo Carvalho de Melo To: Peter Zijlstra Cc: Andi Kleen , jolsa@kernel.org, linux-kernel@vger.kernel.org, Andi Kleen Subject: Re: [PATCH 3/5] perf, tools: Disable branch flags/cycles for --callgraph lbr Message-ID: <20151021180410.GA32514@kernel.org> References: <1445366797-30894-1-git-send-email-andi@firstfloor.org> <1445366797-30894-3-git-send-email-andi@firstfloor.org> <20151021132742.GF3604@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151021132742.GF3604@twins.programming.kicks-ass.net> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Wed, Oct 21, 2015 at 03:27:42PM +0200, Peter Zijlstra escreveu: > On Tue, Oct 20, 2015 at 11:46:35AM -0700, Andi Kleen wrote: > > From: Andi Kleen > > > > Automatically disable collecting branch flags and cycles with > > --call-graph lbr. This allows avoiding a bunch of extra MSR > > reads in the PMI on Skylake. > > > > When the kernel doesn't support the new flags they are automatically > > cleared in the fallback code. > > > > Signed-off-by: Andi Kleen > > --- > > Arnaldo, ACK? I looked at this yesterday, seems to follow the existing mechanisms for fallbacking on older kernels, etc. Acked-by: Arnaldo Carvalho de Melo > > tools/perf/util/evsel.c | 14 +++++++++++++- > > 1 file changed, 13 insertions(+), 1 deletion(-) > > > > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c > > index 8be867c..e8724b4 100644 > > --- a/tools/perf/util/evsel.c > > +++ b/tools/perf/util/evsel.c > > @@ -36,6 +36,7 @@ static struct { > > bool cloexec; > > bool clockid; > > bool clockid_wrong; > > + bool lbr_flags; > > } perf_missing_features; > > > > static clockid_t clockid; > > @@ -573,7 +574,9 @@ perf_evsel__config_callgraph(struct perf_evsel *evsel, > > } else { > > perf_evsel__set_sample_bit(evsel, BRANCH_STACK); > > attr->branch_sample_type = PERF_SAMPLE_BRANCH_USER | > > - PERF_SAMPLE_BRANCH_CALL_STACK; > > + PERF_SAMPLE_BRANCH_CALL_STACK | > > + PERF_SAMPLE_BRANCH_NO_CYCLES | > > + PERF_SAMPLE_BRANCH_NO_FLAGS; > > } > > } else > > pr_warning("Cannot use LBR callstack with branch stack. " > > @@ -1312,6 +1315,9 @@ fallback_missing_features: > > evsel->attr.mmap2 = 0; > > if (perf_missing_features.exclude_guest) > > evsel->attr.exclude_guest = evsel->attr.exclude_host = 0; > > + if (perf_missing_features.lbr_flags) > > + evsel->attr.branch_sample_type &= ~(PERF_SAMPLE_BRANCH_NO_FLAGS | > > + PERF_SAMPLE_BRANCH_NO_CYCLES); > > retry_sample_id: > > if (perf_missing_features.sample_id_all) > > evsel->attr.sample_id_all = 0; > > @@ -1414,6 +1420,12 @@ try_fallback: > > } else if (!perf_missing_features.sample_id_all) { > > perf_missing_features.sample_id_all = true; > > goto retry_sample_id; > > + } else if (!perf_missing_features.lbr_flags && > > + (evsel->attr.branch_sample_type & > > + (PERF_SAMPLE_BRANCH_NO_CYCLES | > > + PERF_SAMPLE_BRANCH_NO_FLAGS))) { > > + perf_missing_features.lbr_flags = true; > > + goto fallback_missing_features; > > } > > > > out_close: > > -- > > 2.4.3 > >