kernel/lib/Kconfig.debug, branch linux-2.6.23.y

lockstat: documentation

2007-10-07T23:28:43Z

Provide some documentation for CONFIG_LOCK_STAT. Signed-off-by: Peter Zijlstra Acked-by: Ingo Molnar Cc: "Randy.Dunlap" Cc: Rob Landley Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

typo fix Kernel config option

2007-09-25T15:51:04Z

Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Remove the arm26 port

2007-07-31T22:39:39Z

The arm26 port has been in a state where it was far from even compiling for quite some time. Ian Molton agreed with the removal. Signed-off-by: Adrian Bunk Cc: Ian Molton Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lockstat: core infrastructure

2007-07-19T17:04:49Z

Introduce the core lock statistics code. Lock statistics provides lock wait-time and hold-time (as well as the count of corresponding contention and acquisitions events). Also, the first few call-sites that encounter contention are tracked. Lock wait-time is the time spent waiting on the lock. This provides insight into the locking scheme, that is, a heavily contended lock is indicative of a too coarse locking scheme. Lock hold-time is the duration the lock was held, this provides a reference for the wait-time numbers, so they can be put into perspective. 1) lock 2) ... do stuff .. unlock 3) The time between 1 and 2 is the wait-time. The time between 2 and 3 is the hold-time. The lockdep held-lock tracking code is reused, because it already collects locks into meaningful groups (classes), and because it is an existing infrastructure for lock instrumentation. Currently lockdep tracks lock acquisition with two hooks: lock() lock_acquire() _lock() ... code protected by lock ... unlock() lock_release() _unlock() We need to extend this with two more hooks, in order to measure contention. lock_contended() - used to measure contention events lock_acquired() - completion of the contention These are then placed the following way: lock() lock_acquire() if (!_try_lock()) lock_contended() _lock() lock_acquired() ... do locked stuff ... unlock() lock_release() _unlock() (Note: the try_lock() 'trick' is used to avoid instrumenting all platform dependent lock primitive implementations.) It is also possible to toggle the two lockdep features at runtime using: /proc/sys/kernel/prove_locking /proc/sys/kernel/lock_stat (esp. turning off the O(n^2) prove_locking functionaliy can help) [akpm@linux-foundation.org: build fixes] [akpm@linux-foundation.org: nuke unneeded ifdefs] Signed-off-by: Peter Zijlstra Acked-by: Ingo Molnar Acked-by: Jason Baron Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

SLUB: support slub_debug on by default

2007-07-16T16:05:36Z

Add a new configuration variable CONFIG_SLUB_DEBUG_ON If set then the kernel will be booted by default with slab debugging switched on. Similar to CONFIG_SLAB_DEBUG. By default slab debugging is available but must be enabled by specifying "slub_debug" as a kernel parameter. Also add support to switch off slab debugging for a kernel that was built with CONFIG_SLUB_DEBUG_ON. This works by specifying slub_debug=- as a kernel parameter. Dave Jones wanted this feature. http://marc.info/?l=linux-kernel&m=118072189913045&w=2 [akpm@linux-foundation.org: clean up switch statement] Signed-off-by: Christoph Lameter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

sched: scheduler debugging, enable in Kconfig

2007-07-09T16:52:00Z

enable CONFIG_SCHED_DEBUG in lib/Kconfig.debug. the runtime overhead of this option is very small. Signed-off-by: Ingo Molnar

timer stats: speedups

2007-06-01T15:18:30Z

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

prohibit rcutorture from being compiled into the kernel

2007-05-24T03:14:12Z

There have been a number of instances where people have accidentally compiled rcutorture into the kernel (CONFIG_RCU_TORTURE_TEST=y), which has never been useful, and has often resulted in great frustration. The attached patch prohibits rcutorture from being compiled into the kernel. It may be excluded altogether or compiled as a module. People wishing to have rcutorture hammer their machine immediately upon boot are free to hand-edit lib/Kconfig.debug to remove the "depends on m" line. Thanks to Randy Dunlap for the trick that makes this work. Signed-off-by: Paul E. McKenney Acked-by: Josh Triplett Cc: "Randy.Dunlap" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

fault injection: disable stacktrace filter for x86-64

2007-05-12T17:55:39Z

Disable stacktrace filter support for x86-64 for now. Will be enable when we can get the dwarf2 unwinder back. Signed-off-by: Akinobu Mita Acked-by: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Move LOG_BUF_SHIFT to a more sensible place

2007-05-08T18:15:14Z

Several people have observed that perhaps LOG_BUF_SHIFT should be in a more obvious place than under DEBUG_KERNEL. Under some circumstances (such as the PARISC architecture), DEBUG_KERNEL can increase kernel size, which is an undesirable trade off for something as trivial as increasing the kernel log buffer size. Instead, move LOG_BUF_SHIFT into "General Setup", so that people are more likely to be able to change it such a circumstance that the default buffer size is insufficient. Signed-off-by: Alistair John Strachan Acked-by: Randy Dunlap Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds