Messages in this thread | ![/](/images/icornerl.gif) | | From | Mike Leach <> | Date | Thu, 19 Jan 2023 12:02:54 +0000 | Subject | Re: [PATCH v7 13/15] coresight: events: PERF_RECORD_AUX_OUTPUT_HW_ID used for Trace ID |
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Hi Suzuki
On Thu, 19 Jan 2023 at 11:02, Suzuki K Poulose <suzuki.poulose@arm.com> wrote: > > Hi Mike > > On 16/01/2023 12:49, Mike Leach wrote: > > Use the perf_report_aux_output_id() call to output the CoreSight trace ID > > and associated CPU as a PERF_RECORD_AUX_OUTPUT_HW_ID record in the > > perf.data file. > > > > Signed-off-by: Mike Leach <mike.leach@linaro.org> > > Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> > > --- > > drivers/hwtracing/coresight/coresight-etm-perf.c | 7 +++++++ > > include/linux/coresight-pmu.h | 14 ++++++++++++++ > > 2 files changed, 21 insertions(+) > > > > diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c > > index bdb9ab86173a..12fff661456e 100644 > > --- a/drivers/hwtracing/coresight/coresight-etm-perf.c > > +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c > > @@ -4,6 +4,7 @@ > > * Author: Mathieu Poirier <mathieu.poirier@linaro.org> > > */ > > > > +#include <linux/bitfield.h> > > #include <linux/coresight.h> > > #include <linux/coresight-pmu.h> > > #include <linux/cpumask.h> > > @@ -448,6 +449,7 @@ static void etm_event_start(struct perf_event *event, int flags) > > struct perf_output_handle *handle = &ctxt->handle; > > struct coresight_device *sink, *csdev = per_cpu(csdev_src, cpu); > > struct list_head *path; > > + u64 hw_id; > > > > if (!csdev) > > goto fail; > > @@ -493,6 +495,11 @@ static void etm_event_start(struct perf_event *event, int flags) > > if (source_ops(csdev)->enable(csdev, event, CS_MODE_PERF)) > > goto fail_disable_path; > > > > + /* output cpu / trace ID in perf record */ > > + hw_id = FIELD_PREP(CS_AUX_HW_ID_VERSION_MASK, CS_AUX_HW_ID_CURR_VERSION); > > + hw_id |= FIELD_PREP(CS_AUX_HW_ID_TRACE_ID_MASK, coresight_trace_id_read_cpu_id(cpu)); > > + perf_report_aux_output_id(event, hw_id); > > + > > One minor nit: > > This ends up putting the HWID packet for every single time the event is > scheduled on the CPU and thus we have : > > $ perf report -D | grep OUTPUT_HW_ID > ... > AUX_OUTPUT_HW_ID events: 55 (18.3%) > > We could do the above step only once per CPU for the lifetime of the > event by book keeping the info in event_data. With that we get, one > record per CPU and: > > $ perf report -D | grep OUTPUT_HW_ID > ... > AUX_OUTPUT_HW_ID events: 5 ( 1.9%) > > Here is a quick patch. We can queue this separately if you all are Ok > with this. Thoughts ? >
Seems reasonable given we guarantee the ID <=> CPU association for the lifetime of the perf session.
Regards
Mike
> ---8>--- > > diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c > b/drivers/hwtracing/coresight/coresight-etm-perf.c > index 12fff661456e..5335f3a2b010 100644 > --- a/drivers/hwtracing/coresight/coresight-etm-perf.c > +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c > @@ -495,10 +495,16 @@ static void etm_event_start(struct perf_event > *event, int flags) > if (source_ops(csdev)->enable(csdev, event, CS_MODE_PERF)) > goto fail_disable_path; > > - /* output cpu / trace ID in perf record */ > - hw_id = FIELD_PREP(CS_AUX_HW_ID_VERSION_MASK, > CS_AUX_HW_ID_CURR_VERSION); > - hw_id |= FIELD_PREP(CS_AUX_HW_ID_TRACE_ID_MASK, > coresight_trace_id_read_cpu_id(cpu)); > - perf_report_aux_output_id(event, hw_id); > + /* > + * output cpu / trace ID in perf record, once for the lifetime > + * of the event. > + */ > + if (!cpumask_test_cpu(cpu, &event_data->aux_hwid_done)) { > + cpumask_set_cpu(cpu, &event_data->aux_hwid_done); > + hw_id = FIELD_PREP(CS_AUX_HW_ID_VERSION_MASK, > CS_AUX_HW_ID_CURR_VERSION); > + hw_id |= FIELD_PREP(CS_AUX_HW_ID_TRACE_ID_MASK, > coresight_trace_id_read_cpu_id(cpu)); > + perf_report_aux_output_id(event, hw_id); > + } > > out: > /* Tell the perf core the event is alive */ > diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.h > b/drivers/hwtracing/coresight/coresight-etm-perf.h > index 468f7799ab4f..9b11bb3d96d9 100644 > --- a/drivers/hwtracing/coresight/coresight-etm-perf.h > +++ b/drivers/hwtracing/coresight/coresight-etm-perf.h > @@ -55,6 +55,7 @@ struct etm_filters { > struct etm_event_data { > struct work_struct work; > cpumask_t mask; > + cpumask_t aux_hwid_done; > void *snk_config; > u32 cfg_hash; > struct list_head * __percpu *path; > > > > > out: > > /* Tell the perf core the event is alive */ > > event->hw.state = 0; > > diff --git a/include/linux/coresight-pmu.h b/include/linux/coresight-pmu.h > > index 624f4843453e..51ac441a37c3 100644 > > --- a/include/linux/coresight-pmu.h > > +++ b/include/linux/coresight-pmu.h > > @@ -7,6 +7,8 @@ > > #ifndef _LINUX_CORESIGHT_PMU_H > > #define _LINUX_CORESIGHT_PMU_H > > > > +#include <linux/bits.h> > > + > > #define CORESIGHT_ETM_PMU_NAME "cs_etm" > > > > /* > > @@ -43,4 +45,16 @@ > > #define ETM4_CFG_BIT_RETSTK 12 > > #define ETM4_CFG_BIT_VMID_OPT 15 > > > > +/* > > + * Interpretation of the PERF_RECORD_AUX_OUTPUT_HW_ID payload. > > + * Used to associate a CPU with the CoreSight Trace ID. > > + * [07:00] - Trace ID - uses 8 bits to make value easy to read in file. > > + * [59:08] - Unused (SBZ) > > + * [63:60] - Version > > + */ > > +#define CS_AUX_HW_ID_TRACE_ID_MASK GENMASK_ULL(7, 0) > > +#define CS_AUX_HW_ID_VERSION_MASK GENMASK_ULL(63, 60) > > + > > +#define CS_AUX_HW_ID_CURR_VERSION 0 > > + > > #endif >
-- Mike Leach Principal Engineer, ARM Ltd. Manchester Design Centre. UK
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