From c1a834dc704763673df10282995257f2de93cbe9 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Fri, 1 Jun 2007 00:47:16 -0700 Subject: timer stats: speedups Make timer-stats have almost zero overhead when enabled in the config but not used. (this way distros can enable it more easily) Also update the documentation about overhead of timer_stats - it was written for the first version which had a global lock and a linear list walk based lookup ;-) Signed-off-by: Ingo Molnar Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/Kconfig.debug | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'lib/Kconfig.debug') diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 1ba77ca7d165..da95e10cfd70 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -126,7 +126,10 @@ config TIMER_STATS reprogrammed. The statistics can be read from /proc/timer_stats. The statistics collection is started by writing 1 to /proc/timer_stats, writing 0 stops it. This feature is useful to collect information - about timer usage patterns in kernel and userspace. + about timer usage patterns in kernel and userspace. This feature + is lightweight if enabled in the kernel config but not activated + (it defaults to deactivated on bootup and will only be activated + if some application like powertop activates it explicitly). config DEBUG_SLAB bool "Debug slab memory allocations" -- cgit v1.2.3