i915/guc: Ensure busyness counter increases motonically

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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: 77cdd054dd ("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>
Link: https://patchwork.freedesktop.org/patch/msgid/20241127174006.190128-3-umesh.nerlige.ramappa@intel.com

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Umesh Nerlige Ramappa 2024-11-27 09:40:05 -08:00

parent abd318237f

commit cf907f6d29

2 changed files with 9 additions and 1 deletions

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5

drivers/gpu/drm/i915/gt/intel_engine_types.h

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5

drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c

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