diff options
| author | Ingo Molnar <mingo@elte.hu> | 2007-06-01 00:47:16 -0700 |
|---|---|---|
| committer | Chris Wright <chrisw@sous-sol.org> | 2007-06-11 11:36:48 -0700 |
| commit | cf019da09936867c2eea7bc75cf1b1d07e5827d3 (patch) | |
| tree | 21c2ee704b71b66a30063c5f563439c32f228825 /lib | |
| parent | 7434011f268211af4a1e4977f5a1eb2004b1a690 (diff) | |
[PATCH] 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 ;-)
Andrew says:
And this. Not a bugfix, but trivial and obvious and apparently some
distros don't want to enable timer_stats because of the performance
issue, but powertop uses timer_stats.
Ingo replies:
seconded. I have tested this with and without CONFIG_TIMER_STATS, with
and without timer_stats collection activated.
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>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Kconfig.debug | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 3f3e7403dcac..c93a50246ae8 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -143,7 +143,10 @@ 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" |