| Message ID | 20211026134022.20597-1-anshuman.gupta@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | i915/selftest: Disable irq to calc eng timestamp | expand |
A couple of comments below, after addressing those this is: Reviewed-by: Badal Nilawar <badal.nilawar@intel.com> On 26-10-2021 19:10, Anshuman Gupta wrote: > gt_pm selftest calculates engine ticks cycles and wall time > cycles by delta of respective engine elapsed TIMESTAMP and ktime > for period of 1000us. > It compares the engine ticks cycles with wall time cycles. > > Disable local cpu interrupt so that interrupt handler > should not preempt the measure_clocks() to calculate > correct engine ticks cycles. > > Suggested-by: Chris P Wilson<chris.p.wilson@intel.com> > Signed-off-by: Anshuman Gupta<anshuman.gupta@intel.com> > --- > drivers/gpu/drm/i915/gt/selftest_gt_pm.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/gpu/drm/i915/gt/selftest_gt_pm.c b/drivers/gpu/drm/i915/gt/selftest_gt_pm.c > index b9441217ca3d..9cf76398bdf5 100644 > --- a/drivers/gpu/drm/i915/gt/selftest_gt_pm.c > +++ b/drivers/gpu/drm/i915/gt/selftest_gt_pm.c > @@ -43,6 +43,7 @@ static void measure_clocks(struct intel_engine_cs *engine, > int i; > > for (i = 0; i < 5; i++) { > + local_irq_disable(); How about saving interrupt state before disabling it. Use local_irq_save here. > preempt_disable(); > cycles[i] = -ENGINE_READ_FW(engine, RING_TIMESTAMP); > dt[i] = ktime_get(); > @@ -52,6 +53,7 @@ static void measure_clocks(struct intel_engine_cs *engine, > dt[i] = ktime_sub(ktime_get(), dt[i]); > cycles[i] += ENGINE_READ_FW(engine, RING_TIMESTAMP); > preempt_enable(); > + local_irq_enable(); Use local_irq_restore here. > } > > /* Use the median of both cycle/dt; close enough */
diff --git a/drivers/gpu/drm/i915/gt/selftest_gt_pm.c b/drivers/gpu/drm/i915/gt/selftest_gt_pm.c index b9441217ca3d..9cf76398bdf5 100644 --- a/drivers/gpu/drm/i915/gt/selftest_gt_pm.c +++ b/drivers/gpu/drm/i915/gt/selftest_gt_pm.c @@ -43,6 +43,7 @@ static void measure_clocks(struct intel_engine_cs *engine, int i; for (i = 0; i < 5; i++) { + local_irq_disable(); preempt_disable(); cycles[i] = -ENGINE_READ_FW(engine, RING_TIMESTAMP); dt[i] = ktime_get(); @@ -52,6 +53,7 @@ static void measure_clocks(struct intel_engine_cs *engine, dt[i] = ktime_sub(ktime_get(), dt[i]); cycles[i] += ENGINE_READ_FW(engine, RING_TIMESTAMP); preempt_enable(); + local_irq_enable(); } /* Use the median of both cycle/dt; close enough */
gt_pm selftest calculates engine ticks cycles and wall time cycles by delta of respective engine elapsed TIMESTAMP and ktime for period of 1000us. It compares the engine ticks cycles with wall time cycles. Disable local cpu interrupt so that interrupt handler should not preempt the measure_clocks() to calculate correct engine ticks cycles. Suggested-by: Chris P Wilson <chris.p.wilson@intel.com> Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com> --- drivers/gpu/drm/i915/gt/selftest_gt_pm.c | 2 ++ 1 file changed, 2 insertions(+)