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Commit 06d9e908 authored by venkatesh.pallipadi@intel.com's avatar venkatesh.pallipadi@intel.com Committed by Andi Kleen
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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: default avatarVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: default avatarAndi Kleen <ak@linux.intel.com>
parent 320eee77

drivers/cpuidle/governors/ladder.c

+12 −0
Original line number Diff line number Diff line
@@ -98,6 +98,18 @@ static int ladder_select_state(struct cpuidle_device *dev) 
	}



	/* 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 &&

	    last_residency < last_state->threshold.demotion_time) {

		last_state->stats.demotion_count++;