[igt-dev] [PATCH i-g-t 4/4] lib/i915/perf: don't forget last timeline element

[Umesh Nerlige Ramappa]

On Mon, Dec 28, 2020 at 05:19:40AM +0200, Lionel Landwerlin wrote:
>We're currently dropping the last element of the timeline.

Inside the for-loop we append timeline events on context switches 
indicating what context ran and for how long, but that's not the case 
for the append_timeline_event outside the for-loop.

Does the one outside indicate how long last_ctx_id ran before capture 
ended (or we ran out of records)? Is it possible for the user to 
distinguish the two? Just thinking out loud.

Otherwise:

Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa at intel.com>

Thanks,
Umesh
>
>Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
>Fixes: 43116ee368585d ("lib/i915-perf: add i915 perf data reader")
>---
> lib/i915/perf_data_reader.c | 27 ++++++++++++++++++---------
> 1 file changed, 18 insertions(+), 9 deletions(-)
>
>diff --git a/lib/i915/perf_data_reader.c b/lib/i915/perf_data_reader.c
>index 4b68fb502..065fe6066 100644
>--- a/lib/i915/perf_data_reader.c
>+++ b/lib/i915/perf_data_reader.c
>@@ -298,17 +298,23 @@ static void
> generate_cpu_events(struct intel_perf_data_reader *reader)
> {
> 	uint32_t last_header_idx = 0;
>-	const struct drm_i915_perf_record_header *last_header = reader->records[0];
>+	const struct drm_i915_perf_record_header *last_header = reader->records[0],
>+		*current_header = reader->records[0];
>+	const uint8_t *start_report, *end_report;
>+	uint32_t last_ctx_id, current_ctx_id;
>+	uint64_t gpu_ts_start, gpu_ts_end;
>
> 	for (uint32_t i = 1; i < reader->n_records; i++) {
>-		const struct drm_i915_perf_record_header *current_header =
>-			reader->records[i];
>-		const uint8_t *start_report = (const uint8_t *) (last_header + 1),
>-			*end_report = (const uint8_t *) (current_header + 1);
>-		uint32_t last_ctx_id = oa_report_ctx_id(&reader->devinfo, start_report),
>-			current_ctx_id = oa_report_ctx_id(&reader->devinfo, end_report);
>-		uint64_t gpu_ts_start = oa_report_timestamp(start_report),
>-			gpu_ts_end = oa_report_timestamp(end_report);
>+		current_header = reader->records[i];
>+
>+		start_report = (const uint8_t *) (last_header + 1);
>+		end_report = (const uint8_t *) (current_header + 1);
>+
>+		last_ctx_id = oa_report_ctx_id(&reader->devinfo, start_report);
>+		current_ctx_id = oa_report_ctx_id(&reader->devinfo, end_report);
>+
>+		gpu_ts_start = oa_report_timestamp(start_report);
>+		gpu_ts_end = oa_report_timestamp(end_report);
>
> 		if (last_ctx_id == current_ctx_id)
> 			continue;
>@@ -318,6 +324,9 @@ generate_cpu_events(struct intel_perf_data_reader *reader)
> 		last_header = current_header;
> 		last_header_idx = i;
> 	}
>+
>+	if (last_header != current_header)
>+		append_timeline_event(reader, gpu_ts_start, gpu_ts_end, last_header_idx, reader->n_records - 1, last_ctx_id);
> }
>
> static void
>-- 
>2.30.0.rc2
>