Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes: > In our tests where we measure the elapsed time on both the CPU and CS > using a udelay, our CS results match the udelay much more accurately > than the ktime (even when using ktime_get_fast_ns). With preemption > disabled, we can go one step lower than ktime and use local_clock. > > Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/2919 > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > --- > drivers/gpu/drm/i915/gt/selftest_engine_pm.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/gt/selftest_engine_pm.c b/drivers/gpu/drm/i915/gt/selftest_engine_pm.c > index ca080445695e..c3d965279fc3 100644 > --- a/drivers/gpu/drm/i915/gt/selftest_engine_pm.c > +++ b/drivers/gpu/drm/i915/gt/selftest_engine_pm.c > @@ -112,11 +112,11 @@ static int __measure_timestamps(struct intel_context *ce, > > /* Run the request for a 100us, sampling timestamps before/after */ > preempt_disable(); Do you need to promote this to local_irq_disable() ? -Mika > - *dt = ktime_get_raw_fast_ns(); > + *dt = local_clock(); > write_semaphore(&sema[2], 0); > udelay(100); > + *dt = local_clock() - *dt; > write_semaphore(&sema[2], 1); > - *dt = ktime_get_raw_fast_ns() - *dt; > preempt_enable(); > > if (i915_request_wait(rq, 0, HZ / 2) < 0) { > -- > 2.20.1 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/intel-gfx _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
