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cpuidle: Make ladder governor honor latency requirements fully 

ladder governor only honored latency requirement when promoting C-states.
Instead. it should check for latency requirement on each idle call,
and demote to appropriate C-state when there is a latency requirement change.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
This commit is contained in:
venkatesh.pallipadi@intel.com 2008-07-30 19:21:44 -07:00 committed by Andi Kleen
parent 320eee7763
commit 06d9e908b2
1 changed files with 12 additions and 0 deletions
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12
drivers/cpuidle/governors/ladder.c
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@ -98,6 +98,18 @@ static int ladder_select_state(struct cpuidle_device *dev)
} }
/* consider demotion */ /* consider demotion */
if (last_idx > CPUIDLE_DRIVER_STATE_START &&
dev->states[last_idx].exit_latency > latency_req) {
int i;
for (i = last_idx - 1; i > CPUIDLE_DRIVER_STATE_START; i--) {
if (dev->states[i].exit_latency <= latency_req)
break;
}
ladder_do_selection(ldev, last_idx, i);
return i;
}
if (last_idx > CPUIDLE_DRIVER_STATE_START && if (last_idx > CPUIDLE_DRIVER_STATE_START &&
last_residency < last_state->threshold.demotion_time) { last_residency < last_state->threshold.demotion_time) {
last_state->stats.demotion_count++; last_state->stats.demotion_count++;