Messages in this thread | | | Subject | Re: [PATCH v2 02/17] perf tools: Configure timestsamp generation in CPU-wide mode | From | Suzuki K Poulose <> | Date | Fri, 7 Jun 2019 10:41:48 +0100 |
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On 24/05/2019 18:34, Mathieu Poirier wrote: > When operating in CPU-wide mode tracers need to generate timestamps in > order to correlate the code being traced on one CPU with what is executed > on other CPUs. > > Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org> > --- > tools/perf/arch/arm/util/cs-etm.c | 57 +++++++++++++++++++++++++++++++ > 1 file changed, 57 insertions(+) > > diff --git a/tools/perf/arch/arm/util/cs-etm.c b/tools/perf/arch/arm/util/cs-etm.c > index 3912f0bf04ed..be1e4f20affa 100644 > --- a/tools/perf/arch/arm/util/cs-etm.c > +++ b/tools/perf/arch/arm/util/cs-etm.c > @@ -99,6 +99,54 @@ static int cs_etm_set_context_id(struct auxtrace_record *itr, > return err; > } > > +static int cs_etm_set_timestamp(struct auxtrace_record *itr, > + struct perf_evsel *evsel, int cpu) > +{ > + struct cs_etm_recording *ptr; > + struct perf_pmu *cs_etm_pmu; > + char path[PATH_MAX]; > + int err = -EINVAL; > + u32 val; > + > + ptr = container_of(itr, struct cs_etm_recording, itr); > + cs_etm_pmu = ptr->cs_etm_pmu; > + > + if (!cs_etm_is_etmv4(itr, cpu)) > + goto out; > + > + /* Get a handle on TRCIRD0 */ > + snprintf(path, PATH_MAX, "cpu%d/%s", > + cpu, metadata_etmv4_ro[CS_ETMV4_TRCIDR0]); > + err = perf_pmu__scan_file(cs_etm_pmu, path, "%x", &val); > + > + /* There was a problem reading the file, bailing out */ > + if (err != 1) { > + pr_err("%s: can't read file %s\n", > + CORESIGHT_ETM_PMU_NAME, path); > + goto out; > + } > + > + /* > + * TRCIDR0.TSSIZE, bit [28-24], indicates whether global timestamping > + * is supported: > + * 0b00000 Global timestamping is not implemented > + * 0b00110 Implementation supports a maximum timestamp of 48bits. > + * 0b01000 Implementation supports a maximum timestamp of 64bits. > + */ > + val &= GENMASK(28, 24); > + if (!val) { > + err = -EINVAL; > + goto out; > + } > + > + /* All good, let the kernel know */ > + evsel->attr.config |= (1 << ETM_OPT_TS); > + err = 0; > + > +out: > + return err; > +} > + > static int cs_etm_set_option(struct auxtrace_record *itr, > struct perf_evsel *evsel, u32 option) > { > @@ -118,6 +166,11 @@ static int cs_etm_set_option(struct auxtrace_record *itr, > if (err) > goto out; > break; > + case ETM_OPT_TS: > + err = cs_etm_set_timestamp(itr, evsel, i); > + if (err) > + goto out; > + break; > default: > goto out; > } > @@ -343,6 +396,10 @@ static int cs_etm_recording_options(struct auxtrace_record *itr, > err = cs_etm_set_option(itr, cs_etm_evsel, ETM_OPT_CTXTID); > if (err) > goto out; > + > + err = cs_etm_set_option(itr, cs_etm_evsel, ETM_OPT_TS); > + if (err) > + goto out;
nit: Could we not do this in one shot, say :
cs_etm_set_option(itr, cs_etm_evsel, ETM_OPT_TS | ETM_OPT_CTXTID) ?
rather than iterating over the per-CPU events twice ? The cs_etm_set_option() could simply replace the switch() to :
if (option & ETM_OPT_1) do_something_for_1() if (option & ETM_OPT_2) do_something_for_2(); if (option & ~(ETM_OPT_1 | ETM_OPT_2 |...)) /* do unsupported option */
Cheers Suzuki
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