Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx> writes: > cpuidle accounts the idle time for the C-state it was trying to enter and > not to the actual state that the driver eventually entered. The driver may > select a different state than the one chosen by cpuidle due to > constraints like bus-mastering, etc. > > Change the time acounting code to look at the dev->last_state after > returning from target_state->enter(). Driver can modify dev->last_state > internally, inside the enter routine to reflect the actual C-state > entered. > > Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx> > > --- > drivers/cpuidle/cpuidle.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > Index: tip/drivers/cpuidle/cpuidle.c > =================================================================== > --- tip.orig/drivers/cpuidle/cpuidle.c 2008-09-23 13:52:59.000000000 -0700 > +++ tip/drivers/cpuidle/cpuidle.c 2008-09-23 14:22:43.000000000 -0700 > @@ -71,8 +71,11 @@ static void cpuidle_idle_call(void) > target_state = &dev->states[next_state]; > > /* enter the state and update stats */ > - dev->last_residency = target_state->enter(dev, target_state); > dev->last_state = target_state; > + dev->last_residency = target_state->enter(dev, target_state); > + if (dev->last_state) > + target_state = dev->last_state; > + > target_state->time += (unsigned long long)dev->last_residency; > target_state->usage++; Under what conditions would the enter hook set dev->last_sate to NULL? Having the check seems to indicate it's possilble. A minor nit-pick... why not explicitly do the accounting using 'last_state' like below. While functionally the same as above, this makes it makes it more explicit when reading the code that the accounting is done using 'last_state' and not 'target_state.' Kevin diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index 5ce07b5..c1294f5 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -67,10 +67,10 @@ static void cpuidle_idle_call(void) target_state = &dev->states[next_state]; /* enter the state and update stats */ - dev->last_residency = target_state->enter(dev, target_state); dev->last_state = target_state; - target_state->time += (unsigned long long)dev->last_residency; - target_state->usage++; + dev->last_residency = target_state->enter(dev, target_state); + dev->last_state->time += (unsigned long long)dev->last_residency; + dev->last_state->usage++; /* give the governor an opportunity to reflect on the outcome */ if (cpuidle_curr_governor->reflect) _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
