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| author | Boris Ostrovsky <boris.ostrovsky@amd.com> | 2012-03-13 19:55:09 +0100 |
|---|---|---|
| committer | Len Brown <len.brown@intel.com> | 2012-03-30 03:23:01 -0400 |
| commit | 1a022e3f1be11730bd8747b1af96a0274bf6356e (patch) | |
| tree | d3c95b68626ac7d963ac3a85a07dae1cfc011906 /drivers/cpuidle | |
| parent | e07510585a88c0f6c6c728e2e006aa913496d4ae (diff) | |
| download | linux-1a022e3f1be11730bd8747b1af96a0274bf6356e.tar.gz linux-1a022e3f1be11730bd8747b1af96a0274bf6356e.tar.bz2 linux-1a022e3f1be11730bd8747b1af96a0274bf6356e.zip | |
idle, x86: Allow off-lined CPU to enter deeper C states
Currently when a CPU is off-lined it enters either MWAIT-based idle or,
if MWAIT is not desired or supported, HLT-based idle (which places the
processor in C1 state). This patch allows processors without MWAIT
support to stay in states deeper than C1.
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@amd.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'drivers/cpuidle')
| -rw-r--r-- | drivers/cpuidle/cpuidle.c | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index f7cab5e9c4d6..3e146b2ada4a 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -72,6 +72,34 @@ typedef int (*cpuidle_enter_t)(struct cpuidle_device *dev, static cpuidle_enter_t cpuidle_enter_ops; /** + * cpuidle_play_dead - cpu off-lining + * + * Only returns in case of an error + */ +int cpuidle_play_dead(void) +{ + struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices); + struct cpuidle_driver *drv = cpuidle_get_driver(); + int i, dead_state = -1; + int power_usage = -1; + + /* Find lowest-power state that supports long-term idle */ + for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) { + struct cpuidle_state *s = &drv->states[i]; + + if (s->power_usage < power_usage && s->enter_dead) { + power_usage = s->power_usage; + dead_state = i; + } + } + + if (dead_state != -1) + return drv->states[dead_state].enter_dead(dev, dead_state); + + return -ENODEV; +} + +/** * cpuidle_idle_call - the main idle loop * * NOTE: no locks or semaphores should be used here |