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| author | Len Brown <len.brown@intel.com> | 2015-07-31 19:46:17 +0300 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2015-08-01 00:46:05 +0300 |
| commit | 2fd77fff4b440c29b48c31db0ce2aec7d319959f (patch) | |
| tree | fe1c131b86a1cefe66e2ed2b7641b8c8db78c757 | |
| parent | 019d8817b1b064c2bacfbcf40fc68184438ad05a (diff) | |
| download | linux-2fd77fff4b440c29b48c31db0ce2aec7d319959f.tar.xz | |
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 <len.brown@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
| -rw-r--r-- | kernel/power/Kconfig | 10 | ||||
| -rw-r--r-- | kernel/power/suspend.c | 2 |
2 files changed, 12 insertions, 0 deletions
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); |