From 6ce12a977b7e484540482febe47d1e65f7427abf Mon Sep 17 00:00:00 2001 From: SungEun Kim Date: Fri, 3 Jul 2015 15:57:20 +0900 Subject: PM / autosleep: Use workqueue for user space wakeup sources garbage collector The synchronous synchronize_rcu() in wakeup_source_remove() makes user process which writes to /sys/kernel/wake_unlock blocked sometimes. For example, when android eventhub tries to release a wakelock, this blocking process can occur, and eventhub can't get input events for a while. Using a work item instead of direct function call at pm_wake_unlock() can prevent this unnecessary delay from happening. Signed-off-by: SungEun Kim Signed-off-by: Rafael J. Wysocki --- kernel/power/wakelock.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/kernel/power/wakelock.c b/kernel/power/wakelock.c index 019069c84ff6..1896386e16bb 100644 --- a/kernel/power/wakelock.c +++ b/kernel/power/wakelock.c @@ -17,6 +17,7 @@ #include #include #include +#include #include "power.h" @@ -83,7 +84,9 @@ static inline void decrement_wakelocks_number(void) {} #define WL_GC_COUNT_MAX 100 #define WL_GC_TIME_SEC 300 +static void __wakelocks_gc(struct work_struct *work); static LIST_HEAD(wakelocks_lru_list); +static DECLARE_WORK(wakelock_work, __wakelocks_gc); static unsigned int wakelocks_gc_count; static inline void wakelocks_lru_add(struct wakelock *wl) @@ -96,13 +99,12 @@ static inline void wakelocks_lru_most_recent(struct wakelock *wl) list_move(&wl->lru, &wakelocks_lru_list); } -static void wakelocks_gc(void) +static void __wakelocks_gc(struct work_struct *work) { struct wakelock *wl, *aux; ktime_t now; - if (++wakelocks_gc_count <= WL_GC_COUNT_MAX) - return; + mutex_lock(&wakelocks_lock); now = ktime_get(); list_for_each_entry_safe_reverse(wl, aux, &wakelocks_lru_list, lru) { @@ -127,6 +129,16 @@ static void wakelocks_gc(void) } } wakelocks_gc_count = 0; + + mutex_unlock(&wakelocks_lock); +} + +static void wakelocks_gc(void) +{ + if (++wakelocks_gc_count <= WL_GC_COUNT_MAX) + return; + + schedule_work(&wakelock_work); } #else /* !CONFIG_PM_WAKELOCKS_GC */ static inline void wakelocks_lru_add(struct wakelock *wl) {} -- cgit 1.4.1 From 2fd77fff4b440c29b48c31db0ce2aec7d319959f Mon Sep 17 00:00:00 2001 From: Len Brown Date: Fri, 31 Jul 2015 12:46:17 -0400 Subject: PM / suspend: make sync() on suspend-to-RAM build-time optional The Linux kernel suspend path has traditionally invoked sys_sync() before freezing user threads. But sys_sync() can be expensive, and some user-space OS's do not want the kernel to pay the cost of sys_sync() on every suspend -- preferring invoke sync() from user-space if/when they want it. So make sys_sync on suspend build-time optional. The default is unchanged. Signed-off-by: Len Brown Signed-off-by: Rafael J. Wysocki --- kernel/power/Kconfig | 10 ++++++++++ kernel/power/suspend.c | 2 ++ 2 files changed, 12 insertions(+) (limited to 'kernel') diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig index 9e302315e33d..02e8dfaa1ce2 100644 --- a/kernel/power/Kconfig +++ b/kernel/power/Kconfig @@ -18,6 +18,16 @@ config SUSPEND_FREEZER Turning OFF this setting is NOT recommended! If in doubt, say Y. +config SUSPEND_SKIP_SYNC + bool "Skip kernel's sys_sync() on suspend to RAM/standby" + depends on SUSPEND + depends on EXPERT + help + Skip the kernel sys_sync() before freezing user processes. + Some systems prefer not to pay this cost on every invocation + of suspend, or they are content with invoking sync() from + user-space before invoking suspend. Say Y if that's your case. + config HIBERNATE_CALLBACKS bool diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c index 53266b729fd9..7e4cda4a8dd9 100644 --- a/kernel/power/suspend.c +++ b/kernel/power/suspend.c @@ -484,11 +484,13 @@ static int enter_state(suspend_state_t state) if (state == PM_SUSPEND_FREEZE) freeze_begin(); +#ifndef CONFIG_SUSPEND_SKIP_SYNC trace_suspend_resume(TPS("sync_filesystems"), 0, true); printk(KERN_INFO "PM: Syncing filesystems ... "); sys_sync(); printk("done.\n"); trace_suspend_resume(TPS("sync_filesystems"), 0, false); +#endif pr_debug("PM: Preparing system for sleep (%s)\n", pm_states[state]); error = suspend_prepare(state); -- cgit 1.4.1