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Message-ID: <b14b7507-e20a-2223-b772-fc865e5c9558@arm.com>
Date: Thu, 19 Jan 2023 11:02:41 +0000
From: Suzuki K Poulose <suzuki.poulose@....com>
To: Mike Leach <mike.leach@...aro.org>, coresight@...ts.linaro.org,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Leo Yan <leo.yan@...aro.org>, James Clark <james.clark@....com>
Cc: mathieu.poirier@...aro.org, peterz@...radead.org, mingo@...hat.com,
acme@...nel.org, linux-perf-users@...r.kernel.org,
leo.yan@...aro.org, quic_jinlmao@...cinc.com
Subject: Re: [PATCH v7 13/15] coresight: events: PERF_RECORD_AUX_OUTPUT_HW_ID
used for Trace ID
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@...aro.org>
> Reviewed-by: Suzuki K Poulose <suzuki.poulose@....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@...aro.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 ?
---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
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