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 <[email protected]> > > > > 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 <[email protected]> > > --- > > 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 <[email protected]> > > 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 > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
