[PATCH v3 0/6] perf arm-spe: Enable timestamp

[PATCH v3 0/6] perf arm-spe: Enable timestamp

[Leo Yan]

This patch set is to enable timestamp for Arm SPE trace.  It reads out
TSC parameters from the TIME_CONV event, the parameters are used for
conversion between timer counter and kernel time and which is applied
for Arm SPE samples.

This version dropped the change for adding hardware clock parameters
into auxtrace info, alternatively, it utilizes the TIME_CONV event to
extract the clock parameters which is used for timestamp calculation.

This patch set can be clearly applied on perf/core branch with:

  commit 2c0cb9f56020 ("perf test: Add a shell test for 'perf stat --bpf-counters' new option")

Ths patch series has been tested on Hisilicon D06 platform.

Changes from v2:
* Changed to use TIME_CONV event for extracing clock parameters (Al).

Changes from v1:
* Rebased patch series on the latest perf/core branch;
* Fixed the patch for dumping TSC parameters to support both the
  older and new auxtrace info format.


Leo Yan (6):
  perf arm-spe: Remove unused enum value ARM_SPE_PER_CPU_MMAPS
  perf arm-spe: Save clock parameters from TIME_CONV event
  perf arm-spe: Convert event kernel time to counter value
  perf arm-spe: Assign kernel time to synthesized event
  perf arm-spe: Bail out if the trace is later than perf event
  perf arm-spe: Don't wait for PERF_RECORD_EXIT event

 tools/perf/util/arm-spe.c | 66 +++++++++++++++++++++++++++++++++------
 tools/perf/util/arm-spe.h |  1 -
 2 files changed, 56 insertions(+), 11 deletions(-)

-- 
2.25.1


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[PATCH v3 1/6] perf arm-spe: Remove unused enum value ARM_SPE_PER_CPU_MMAPS

[Leo Yan]

The enum value 'ARM_SPE_PER_CPU_MMAPS' is never used so remove it.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
---
 tools/perf/util/arm-spe.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/tools/perf/util/arm-spe.h b/tools/perf/util/arm-spe.h
index 98d3235781c3..105ce0ea0a01 100644
--- a/tools/perf/util/arm-spe.h
+++ b/tools/perf/util/arm-spe.h
@@ -11,7 +11,6 @@
 
 enum {
 	ARM_SPE_PMU_TYPE,
-	ARM_SPE_PER_CPU_MMAPS,
 	ARM_SPE_AUXTRACE_PRIV_MAX,
 };
 
-- 
2.25.1


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[PATCH v3 2/6] perf arm-spe: Save clock parameters from TIME_CONV event

[Leo Yan]

During the recording phase, "perf record" tool synthesizes event
PERF_RECORD_TIME_CONV for the hardware clock parameters and saves the
event into the data file.

Afterwards, when processing the data file, the event TIME_CONV will be
processed at the very early time and is stored into session context.

This patch extracts these parameters from the session context and saves
into the structure "spe->tc" with the type perf_tsc_conversion, so that
the parameters are ready for conversion between clock counter and time
stamp.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
---
 tools/perf/util/arm-spe.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index 2539d4baec44..b48816d5c0b4 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -26,6 +26,7 @@
 #include "symbol.h"
 #include "thread.h"
 #include "thread-stack.h"
+#include "tsc.h"
 #include "tool.h"
 #include "util/synthetic-events.h"
 
@@ -45,6 +46,8 @@ struct arm_spe {
 	struct machine			*machine;
 	u32				pmu_type;
 
+	struct perf_tsc_conversion	tc;
+
 	u8				timeless_decoding;
 	u8				data_queued;
 
@@ -1027,6 +1030,22 @@ int arm_spe_process_auxtrace_info(union perf_event *event,
 	spe->pmu_type = auxtrace_info->priv[ARM_SPE_PMU_TYPE];
 
 	spe->timeless_decoding = arm_spe__is_timeless_decoding(spe);
+
+	/*
+	 * The synthesized event PERF_RECORD_TIME_CONV has been handled
+	 * ahead and the parameters for hardware clock are stored in
+	 * the session context.  Passes these parameters to the structure
+	 * perf_tsc_conversion in "spe->tc", which is used for later
+	 * conversion between clock counter and timestamp.
+	 */
+	spe->tc.time_shift = session->time_conv.time_shift;
+	spe->tc.time_mult = session->time_conv.time_mult;
+	spe->tc.time_zero = session->time_conv.time_zero;
+	spe->tc.time_cycles = session->time_conv.time_cycles;
+	spe->tc.time_mask = session->time_conv.time_mask;
+	spe->tc.cap_user_time_zero = session->time_conv.cap_user_time_zero;
+	spe->tc.cap_user_time_short = session->time_conv.cap_user_time_short;
+
 	spe->auxtrace.process_event = arm_spe_process_event;
 	spe->auxtrace.process_auxtrace_event = arm_spe_process_auxtrace_event;
 	spe->auxtrace.flush_events = arm_spe_flush;
-- 
2.25.1


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[PATCH v3 3/6] perf arm-spe: Convert event kernel time to counter value

[Leo Yan]

When handle a perf event, Arm SPE decoder needs to decide if this perf
event is earlier or later than the samples from Arm SPE trace data; to
do comparision, it needs to use the same unit for the time.

This patch converts the event kernel time to arch timer's counter value,
thus it can be used to compare with counter value contained in Arm SPE
Timestamp packet.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
---
 tools/perf/util/arm-spe.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index b48816d5c0b4..f66e10c62473 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -669,7 +669,7 @@ static int arm_spe_process_event(struct perf_session *session,
 	}
 
 	if (sample->time && (sample->time != (u64) -1))
-		timestamp = sample->time;
+		timestamp = perf_time_to_tsc(sample->time, &spe->tc);
 	else
 		timestamp = 0;
 
-- 
2.25.1


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[PATCH v3 4/6] perf arm-spe: Assign kernel time to synthesized event

[Leo Yan]

In current code, it assigns the arch timer counter to the synthesized
samples Arm SPE trace, thus the samples don't contain the kernel time
but only contain the raw counter value.

To fix the issue, this patch converts the timer counter to kernel time
and assigns it to sample timestamp.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
---
 tools/perf/util/arm-spe.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index f66e10c62473..ec7df83b50fd 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -234,7 +234,7 @@ static void arm_spe_prep_sample(struct arm_spe *spe,
 	struct arm_spe_record *record = &speq->decoder->record;
 
 	if (!spe->timeless_decoding)
-		sample->time = speq->timestamp;
+		sample->time = tsc_to_perf_time(record->timestamp, &spe->tc);
 
 	sample->ip = record->from_ip;
 	sample->cpumode = arm_spe_cpumode(spe, sample->ip);
-- 
2.25.1


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[PATCH v3 5/6] perf arm-spe: Bail out if the trace is later than perf event

[Leo Yan]

It's possible that record in Arm SPE trace is later than perf event and
vice versa.  This asks to correlate the perf events and Arm SPE
synthesized events to be processed in the manner of correct timing.

To achieve the time ordering, this patch reverses the flow, it firstly
calls arm_spe_sample() and then calls arm_spe_decode().  By comparing
the timestamp value and detect the perf event is coming earlier than Arm
SPE trace data, it bails out from the decoding loop, the last record is
pushed into auxtrace stack and is deferred to generate sample.  To track
the timestamp, everytime it updates timestamp for the latest record.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
---
 tools/perf/util/arm-spe.c | 37 ++++++++++++++++++++++++++++++++++---
 1 file changed, 34 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index ec7df83b50fd..8facda81a06c 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -434,12 +434,36 @@ static int arm_spe_sample(struct arm_spe_queue *speq)
 static int arm_spe_run_decoder(struct arm_spe_queue *speq, u64 *timestamp)
 {
 	struct arm_spe *spe = speq->spe;
+	struct arm_spe_record *record;
 	int ret;
 
 	if (!spe->kernel_start)
 		spe->kernel_start = machine__kernel_start(spe->machine);
 
 	while (1) {
+		/*
+		 * The usual logic is firstly to decode the packets, and then
+		 * based the record to synthesize sample; but here the flow is
+		 * reversed: it calls arm_spe_sample() for synthesizing samples
+		 * prior to arm_spe_decode().
+		 *
+		 * Two reasons for this code logic:
+		 * 1. Firstly, when setup queue in arm_spe__setup_queue(), it
+		 * has decoded trace data and generated a record, but the record
+		 * is left to generate sample until run to here, so it's correct
+		 * to synthesize sample for the left record.
+		 * 2. After decoding trace data, it needs to compare the record
+		 * timestamp with the coming perf event, if the record timestamp
+		 * is later than the perf event, it needs bail out and pushs the
+		 * record into auxtrace heap, thus the record can be deferred to
+		 * synthesize sample until run to here at the next time; so this
+		 * can correlate samples between Arm SPE trace data and other
+		 * perf events with correct time ordering.
+		 */
+		ret = arm_spe_sample(speq);
+		if (ret)
+			return ret;
+
 		ret = arm_spe_decode(speq->decoder);
 		if (!ret) {
 			pr_debug("No data or all data has been processed.\n");
@@ -453,10 +477,17 @@ static int arm_spe_run_decoder(struct arm_spe_queue *speq, u64 *timestamp)
 		if (ret < 0)
 			continue;
 
-		ret = arm_spe_sample(speq);
-		if (ret)
-			return ret;
+		record = &speq->decoder->record;
 
+		/* Update timestamp for the last record */
+		if (record->timestamp > speq->timestamp)
+			speq->timestamp = record->timestamp;
+
+		/*
+		 * If the timestamp of the queue is later than timestamp of the
+		 * coming perf event, bail out so can allow the perf event to
+		 * be processed ahead.
+		 */
 		if (!spe->timeless_decoding && speq->timestamp >= *timestamp) {
 			*timestamp = speq->timestamp;
 			return 0;
-- 
2.25.1


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[PATCH v3 6/6] perf arm-spe: Don't wait for PERF_RECORD_EXIT event

[Leo Yan]

When decode Arm SPE trace, it waits for PERF_RECORD_EXIT event (the last
perf event) for processing trace data, which is needless and even might
cause logic error, e.g. it might fail to correlate perf events with Arm
SPE events correctly.

So this patch removes the condition checking for PERF_RECORD_EXIT event.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
---
 tools/perf/util/arm-spe.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index 8facda81a06c..5e98a29fcbdb 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -717,11 +717,7 @@ static int arm_spe_process_event(struct perf_session *session,
 					sample->time);
 		}
 	} else if (timestamp) {
-		if (event->header.type == PERF_RECORD_EXIT) {
-			err = arm_spe_process_queues(spe, timestamp);
-			if (err)
-				return err;
-		}
+		err = arm_spe_process_queues(spe, timestamp);
 	}
 
 	return err;
-- 
2.25.1


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Re: [PATCH v3 2/6] perf arm-spe: Save clock parameters from TIME_CONV event

[Leo Yan]

On Sat, Apr 10, 2021 at 01:00:42PM +0800, Leo Yan wrote:
> During the recording phase, "perf record" tool synthesizes event
> PERF_RECORD_TIME_CONV for the hardware clock parameters and saves the
> event into the data file.
> 
> Afterwards, when processing the data file, the event TIME_CONV will be
> processed at the very early time and is stored into session context.
> 
> This patch extracts these parameters from the session context and saves
> into the structure "spe->tc" with the type perf_tsc_conversion, so that
> the parameters are ready for conversion between clock counter and time
> stamp.
> 
> Signed-off-by: Leo Yan <leo.yan@linaro.org>

[...]

> ---
>  tools/perf/util/arm-spe.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
> index 2539d4baec44..b48816d5c0b4 100644
> --- a/tools/perf/util/arm-spe.c
> +++ b/tools/perf/util/arm-spe.c
> @@ -26,6 +26,7 @@
>  #include "symbol.h"
>  #include "thread.h"
>  #include "thread-stack.h"
> +#include "tsc.h"
>  #include "tool.h"
>  #include "util/synthetic-events.h"
>  
> @@ -45,6 +46,8 @@ struct arm_spe {
>  	struct machine			*machine;
>  	u32				pmu_type;
>  
> +	struct perf_tsc_conversion	tc;
> +
>  	u8				timeless_decoding;
>  	u8				data_queued;
>  
> @@ -1027,6 +1030,22 @@ int arm_spe_process_auxtrace_info(union perf_event *event,
>  	spe->pmu_type = auxtrace_info->priv[ARM_SPE_PMU_TYPE];
>  
>  	spe->timeless_decoding = arm_spe__is_timeless_decoding(spe);
> +
> +	/*
> +	 * The synthesized event PERF_RECORD_TIME_CONV has been handled
> +	 * ahead and the parameters for hardware clock are stored in
> +	 * the session context.  Passes these parameters to the structure
> +	 * perf_tsc_conversion in "spe->tc", which is used for later
> +	 * conversion between clock counter and timestamp.
> +	 */
> +	spe->tc.time_shift = session->time_conv.time_shift;
> +	spe->tc.time_mult = session->time_conv.time_mult;
> +	spe->tc.time_zero = session->time_conv.time_zero;
> +	spe->tc.time_cycles = session->time_conv.time_cycles;
> +	spe->tc.time_mask = session->time_conv.time_mask;
> +	spe->tc.cap_user_time_zero = session->time_conv.cap_user_time_zero;
> +	spe->tc.cap_user_time_short = session->time_conv.cap_user_time_short;

As Adrain suggested, this patch also should check the size of event
PERF_RECORD_TIME_CONV for backwards-compability.   I will send a new
patch set for this.

Thanks,
Leo

>  	spe->auxtrace.process_event = arm_spe_process_event;
>  	spe->auxtrace.process_auxtrace_event = arm_spe_process_auxtrace_event;
>  	spe->auxtrace.flush_events = arm_spe_flush;
> -- 
> 2.25.1
> 

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