On Thu, Nov 21, 2024 at 04:34:14PM -0800, John Harrison wrote:
On 11/21/2024 16:31, John Harrison wrote:
On 11/18/2024 15:22, Umesh Nerlige Ramappa wrote:
Active busyness of an engine is calculated using gt timestamp and the
context switch in time. While capturing the gt timestamp, it's possible
that the context switches out. This race could result in an active
busyness value that is greater than the actual context runtime
value by a
small amount. This leads to a negative delta and throws off busyness
calculations for the user.
If a subsequent count is smaller than the previous one, just return the
previous one, since we expect the busyness to catch up.
Fixes: 77cdd054dd2c ("drm/i915/pmu: Connect engine busyness stats
from GuC to pmu")
Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@xxxxxxxxx>
Reviewed-by: John Harrison <John.C.Harrison@xxxxxxxxx>
Actually, does this need to be cleared in
__reset_guc_busyness_stats()? If there is a reset and the live value
is returned to zero then you won't get any more updates until it gets
back to where it used to be.
We don't return the live value. We just accumulate the deltas from live
values into stats->total_gt_clks, compare it to stats->total and return
the one that is monotonically increasing.
The stats->total_gt_clks and stats->total are retained across resets, so
we should be good.
Thanks,
Umesh
John.
---
drivers/gpu/drm/i915/gt/intel_engine_types.h | 5 +++++
drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 5 ++++-
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h
b/drivers/gpu/drm/i915/gt/intel_engine_types.h
index ba55c059063d..fe1f85e5dda3 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h
@@ -343,6 +343,11 @@ struct intel_engine_guc_stats {
* @start_gt_clk: GT clock time of last idle to active transition.
*/
u64 start_gt_clk;
+
+ /**
+ * @total: The last value of total returned
+ */
+ u64 total;
};
union intel_engine_tlb_inv_reg {
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 c71aedcbce43..56be9f385270 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -1378,9 +1378,12 @@ static ktime_t guc_engine_busyness(struct
intel_engine_cs *engine, ktime_t *now)
total += intel_gt_clock_interval_to_ns(gt, clk);
}
+ if (total > stats->total)
+ stats->total = total;
+
spin_unlock_irqrestore(&guc->timestamp.lock, flags);
- return ns_to_ktime(total);
+ return ns_to_ktime(stats->total);
}
static void guc_enable_busyness_worker(struct intel_guc *guc)
