lkml.org 
[lkml]   [2015]   [May]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 3/3] cpuidle: Select a different state on tick_broadcast_enter() failures
Date
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

If tick_broadcast_enter() fails in cpuidle_enter_state(),
try to find another idle state to enter instead of invoking
default_idle_call() immediately and returning -EBUSY which
should increase the chances of saving some energy in those
cases.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
drivers/cpuidle/cpuidle.c | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)

Index: linux-pm/drivers/cpuidle/cpuidle.c
===================================================================
--- linux-pm.orig/drivers/cpuidle/cpuidle.c
+++ linux-pm/drivers/cpuidle/cpuidle.c
@@ -73,7 +73,10 @@ int cpuidle_play_dead(void)
}

static int find_deepest_state(struct cpuidle_driver *drv,
- struct cpuidle_device *dev, bool freeze)
+ struct cpuidle_device *dev,
+ unsigned int max_latency,
+ unsigned int forbidden_flags,
+ bool freeze)
{
unsigned int latency_req = 0;
int i, ret = freeze ? -1 : CPUIDLE_DRIVER_STATE_START - 1;
@@ -83,6 +86,8 @@ static int find_deepest_state(struct cpu
struct cpuidle_state_usage *su = &dev->states_usage[i];

if (s->disabled || su->disable || s->exit_latency <= latency_req
+ || s->exit_latency > max_latency
+ || (s->flags & forbidden_flags)
|| (freeze && !s->enter_freeze))
continue;

@@ -100,7 +105,7 @@ static int find_deepest_state(struct cpu
int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
struct cpuidle_device *dev)
{
- return find_deepest_state(drv, dev, false);
+ return find_deepest_state(drv, dev, UINT_MAX, 0, false);
}

static void enter_freeze_proper(struct cpuidle_driver *drv,
@@ -139,7 +144,7 @@ int cpuidle_enter_freeze(struct cpuidle_
* that interrupts won't be enabled when it exits and allows the tick to
* be frozen safely.
*/
- index = find_deepest_state(drv, dev, true);
+ index = find_deepest_state(drv, dev, UINT_MAX, 0, true);
if (index >= 0)
enter_freeze_proper(drv, dev, index);

@@ -168,8 +173,13 @@ int cpuidle_enter_state(struct cpuidle_d
* CPU as a broadcast timer, this call may fail if it is not available.
*/
if (broadcast && tick_broadcast_enter()) {
- default_idle_call();
- return -EBUSY;
+ index = find_deepest_state(drv, dev, target_state->exit_latency,
+ CPUIDLE_FLAG_TIMER_STOP, false);
+ if (index < 0) {
+ default_idle_call();
+ return -EBUSY;
+ }
+ target_state = &drv->states[index];
}

/* Take note of the planned idle state. */

\
 
 \ /
  Last update: 2015-05-10 01:21    [W:0.323 / U:0.244 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site