On Wednesday, June 14, 2017 5:38:32 PM PDT Lionel Landwerlin wrote:
> From: Robert Bragg <rob...@sixbynine.org>
>
> From experimentation in IGT, we found that the OA unit might label
> some report as "idle" (using an invalid context ID), right after a
> report for a given context. Deltas generated by those reports actually
> belong to the previous context, even though they're not labelled as
> such.
>
> This change makes ensure that while reading OA reports, we only
> consider the GPU actually idle after 2 reports with an invalid context
> ID.
>
> Signed-off-by: Lionel Landwerlin <lionel.g.landwer...@intel.com>
> ---
> src/mesa/drivers/dri/i965/brw_performance_query.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_performance_query.c
> b/src/mesa/drivers/dri/i965/brw_performance_query.c
> index d11784c0352..c6574df302a 100644
> --- a/src/mesa/drivers/dri/i965/brw_performance_query.c
> +++ b/src/mesa/drivers/dri/i965/brw_performance_query.c
> @@ -863,6 +863,7 @@ accumulate_oa_reports(struct brw_context *brw,
> struct exec_node *first_samples_node;
> bool in_ctx = true;
> uint32_t ctx_id;
> + int out_duration = 0;
>
> assert(o->Ready);
> assert(obj->oa.map != NULL);
> @@ -937,10 +938,16 @@ accumulate_oa_reports(struct brw_context *brw,
> if (in_ctx && report[2] != ctx_id) {
> DBG("i915 perf: Switch AWAY (observed by ID change)\n");
> in_ctx = false;
> + out_duration = 0;
> } else if (in_ctx == false && report[2] == ctx_id) {
> DBG("i915 perf: Switch TO\n");
> in_ctx = true;
> - add = false;
> +
> + /* We didn't *really* Switch AWAY in the case that we
> + * e.g. saw a single periodic report while idle...
> + */
> + if (out_duration >= 1)
> + add = false;
> } else if (in_ctx) {
> assert(report[2] == ctx_id);
> DBG("i915 perf: Continuation IN\n");
> @@ -948,6 +955,7 @@ accumulate_oa_reports(struct brw_context *brw,
> assert(report[2] != ctx_id);
> DBG("i915 perf: Continuation OUT\n");
> add = false;
> + out_duration++;
> }
> }
>
> Yeesh. Hardware bugs. Great find. Would it make sense to record the commit message as a comment? I guess there's always tig blame... Reviewed-by: Kenneth Graunke <kenn...@whitecape.org>
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