Re: [PATCH 1/3] i915/guc: Reset engine utilization buffer before registration

[John Harrison <john.c.harrison@intel.com>]

On 11/18/2024 15:22, Umesh Nerlige Ramappa wrote:
> On GT reset, we store total busyness counts for all engines and
> re-register the utilization buffer with GuC. At that time we should
> reset the buffer, so that we don't get spurious busyness counts on
> subsequent queries.
>
> To repro this issue, run igt@perf_pmu@busy-hang followed by
> igt@perf_pmu@most-busy-idle-check-all for a couple iterations.
>
> Fixes: 77cdd054dd2c ("drm/i915/pmu: Connect engine busyness stats from GuC to pmu")
> Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>

> ---
>   .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 21 +++++++++++++++++++
>   1 file changed, 21 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> index 353a9167c9a4..c71aedcbce43 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -1243,6 +1243,21 @@ static void __get_engine_usage_record(struct intel_engine_cs *engine,
>   	} while (++i < 6);
>   }
>   
> +static void __set_engine_usage_record(struct intel_engine_cs *engine,
> +				      u32 last_in, u32 id, u32 total)
> +{
> +	struct iosys_map rec_map = intel_guc_engine_usage_record_map(engine);
> +
> +#define record_write(map_, field_, val_) \
> +	iosys_map_wr_field(map_, 0, struct guc_engine_usage_record, field_, val_)
> +
> +	record_write(&rec_map, last_switch_in_stamp, last_in);
> +	record_write(&rec_map, current_context_index, id);
> +	record_write(&rec_map, total_runtime, total);
> +
> +#undef record_write
> +}
> +
>   static void guc_update_engine_gt_clks(struct intel_engine_cs *engine)
>   {
>   	struct intel_engine_guc_stats *stats = &engine->stats.guc;
> @@ -1543,6 +1558,9 @@ static void guc_timestamp_ping(struct work_struct *wrk)
>   
>   static int guc_action_enable_usage_stats(struct intel_guc *guc)
>   {
> +	struct intel_gt *gt = guc_to_gt(guc);
> +	struct intel_engine_cs *engine;
> +	enum intel_engine_id id;
>   	u32 offset = intel_guc_engine_usage_offset(guc);
>   	u32 action[] = {
>   		INTEL_GUC_ACTION_SET_ENG_UTIL_BUFF,
> @@ -1550,6 +1568,9 @@ static int guc_action_enable_usage_stats(struct intel_guc *guc)
>   		0,
>   	};
>   
> +	for_each_engine(engine, gt, id)
> +		__set_engine_usage_record(engine, 0, 0xffffffff, 0);
> +
>   	return intel_guc_send(guc, action, ARRAY_SIZE(action));
>   }
>