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authorIngo Molnar <mingo@elte.hu>2007-06-01 00:47:16 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-06-01 08:18:30 -0700
commitc1a834dc704763673df10282995257f2de93cbe9 (patch)
tree66a0bc5ffbf6732eaa5fc6f554c13b235005c4cd /lib
parent9fcc15ec3c1c287a781a4620e52522b6186f26f6 (diff)
downloadlinux-linaro-c1a834dc704763673df10282995257f2de93cbe9.tar.gz
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 <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/Kconfig.debug5
1 files changed, 4 insertions, 1 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 1ba77ca7d16..da95e10cfd7 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"