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| author | venkatesh.pallipadi@intel.com <venkatesh.pallipadi@intel.com> | 2008-07-30 19:21:43 -0700 |
|---|---|---|
| committer | Andi Kleen <ak@linux.intel.com> | 2008-08-15 21:25:25 +0200 |
| commit | 320eee776357db52d6fcfb11cff985b1976a4595 (patch) | |
| tree | 29859b2e6209a35fc6a735fa4c195e7daeaa1b31 /drivers/cpuidle | |
| parent | a2bd92023357e47f22a34d4cb1635453546662bc (diff) | |
| download | linux-stable-320eee776357db52d6fcfb11cff985b1976a4595.tar.gz linux-stable-320eee776357db52d6fcfb11cff985b1976a4595.tar.bz2 linux-stable-320eee776357db52d6fcfb11cff985b1976a4595.zip | |
cpuidle: Menu governor fix wrong usage of measured_us
There is a bug in menu governor where we have
if (data->elapsed_us < data->elapsed_us + measured_us)
with measured_us already having elapsed_us added in tickless case here
unsigned int measured_us =
cpuidle_get_last_residency(dev) + data->elapsed_us;
Also, it should be last_residency, not measured_us, that need to be used to
do comparing and distinguish between expected & non-expected events.
Refactor menu_reflect() to fix these two problems.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Wei Gang <gang.wei@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Diffstat (limited to 'drivers/cpuidle')
| -rw-r--r-- | drivers/cpuidle/governors/menu.c | 31 |
1 files changed, 19 insertions, 12 deletions
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c index b8f3e21530bd..8d7cf3f31450 100644 --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -74,9 +74,9 @@ static void menu_reflect(struct cpuidle_device *dev) { struct menu_device *data = &__get_cpu_var(menu_devices); int last_idx = data->last_state_idx; - unsigned int measured_us = - cpuidle_get_last_residency(dev) + data->elapsed_us; + unsigned int last_idle_us = cpuidle_get_last_residency(dev); struct cpuidle_state *target = &dev->states[last_idx]; + unsigned int measured_us; /* * Ugh, this idle state doesn't support residency measurements, so we @@ -84,20 +84,27 @@ static void menu_reflect(struct cpuidle_device *dev) * for one full standard timer tick. However, be aware that this * could potentially result in a suboptimal state transition. */ - if (!(target->flags & CPUIDLE_FLAG_TIME_VALID)) - measured_us = USEC_PER_SEC / HZ; + if (unlikely(!(target->flags & CPUIDLE_FLAG_TIME_VALID))) + last_idle_us = USEC_PER_SEC / HZ; - /* Predict time remaining until next break event */ - if (measured_us + BREAK_FUZZ < data->expected_us - target->exit_latency) { - data->predicted_us = max(measured_us, data->last_measured_us); + /* + * measured_us and elapsed_us are the cumulative idle time, since the + * last time we were woken out of idle by an interrupt. + */ + if (data->elapsed_us <= data->elapsed_us + last_idle_us) + measured_us = data->elapsed_us + last_idle_us; + else + measured_us = -1; + + /* Predict time until next break event */ + data->predicted_us = max(measured_us, data->last_measured_us); + + if (last_idle_us + BREAK_FUZZ < + data->expected_us - target->exit_latency) { data->last_measured_us = measured_us; data->elapsed_us = 0; } else { - if (data->elapsed_us < data->elapsed_us + measured_us) - data->elapsed_us = measured_us; - else - data->elapsed_us = -1; - data->predicted_us = max(measured_us, data->last_measured_us); + data->elapsed_us = measured_us; } } |