kernel_optimize_test/lib
Peter Zijlstra f20786ff4d lockstat: core infrastructure
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 <a.p.zijlstra@chello.nl>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 10:04:49 -07:00
..
lzo Add LZO1X algorithm to the kernel 2007-07-10 17:51:13 -07:00
reed_solomon [RSLIB] Support non-canonical GF representations 2007-05-02 11:56:33 +01:00
zlib_deflate
zlib_inflate Fix ppp_deflate issues with recent zlib_inflate changes 2007-05-07 12:13:04 -07:00
.gitignore
argv_split.c add argv_split() 2007-07-18 08:47:40 -07:00
audit.c [PATCH] audit signal recipients 2007-05-11 05:38:25 -04:00
bitmap.c [PATCH] kernel-doc fixes for 2.6.20-git15 (non-drivers) 2007-03-01 14:53:37 -08:00
bitrev.c [PATCH] add MODULE_* attributes to bit reversal library 2006-12-10 10:07:52 -08:00
bug.c generic bug: use show_regs() instead of dump_stack() 2007-07-16 09:05:51 -07:00
bust_spinlocks.c [PATCH] Extract and use wake_up_klogd() 2007-02-11 10:51:34 -08:00
check_signature.c uninline check_signature() 2007-07-16 09:05:50 -07:00
cmdline.c [PATCH] Numerous fixes to kernel-doc info in source files. 2007-02-11 10:51:32 -08:00
cpumask.c Safer nr_node_ids and nr_node_ids determination and initial values 2007-05-07 12:12:51 -07:00
crc7.c CRC7 support 2007-07-17 10:23:04 -07:00
crc16.c
crc32.c [PATCH] crc32: replace bitreverse by bitrev32 2006-12-08 08:28:39 -08:00
crc32defs.h
crc-ccitt.c
crc-itu-t.c CRC ITU-T V.41 2007-05-10 18:24:13 +02:00
ctype.c
debug_locks.c [PATCH] lockdep: better lock debugging 2006-07-03 15:27:01 -07:00
dec_and_lock.c
devres.c iomap: implement pcim_iounmap_regions() 2007-04-28 14:15:58 -04:00
div64.c [S390]: Fix build on 31-bit. 2007-04-25 22:28:53 -07:00
dump_stack.c
extable.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
fault-inject.c simplify the stacktrace code 2007-05-08 11:14:58 -07:00
find_next_bit.c
gen_crc32table.c
genalloc.c Slab allocators: Replace explicit zeroing with __GFP_ZERO 2007-07-17 10:23:02 -07:00
halfmd4.c
hexdump.c hexdump: more output formatting 2007-06-08 17:23:34 -07:00
hweight.c [PATCH] optimize hweight64 for x86_64 2006-09-26 10:52:38 +02:00
idr.c lib: add idr_remove_all 2007-07-16 09:05:34 -07:00
inflate.c [PATCH] x86-64: deflate inflate_dynamic too 2007-05-02 19:27:15 +02:00
int_sqrt.c
iomap_copy.c
iomap.c iomap: make the default iomap functions fail softer 2007-05-04 20:44:23 -07:00
ioremap.c Detach sched.h from mm.h 2007-05-21 09:18:19 -07:00
irq_regs.c [PATCH] irq_reqs: export __irq_regs 2006-10-06 08:53:40 -07:00
Kconfig CRC7 support 2007-07-17 10:23:04 -07:00
Kconfig.debug lockstat: core infrastructure 2007-07-19 10:04:49 -07:00
kernel_lock.c [PATCH] lockdep: prove spinlock rwlock locking correctness 2006-07-03 15:27:04 -07:00
klist.c Driver core: Don't call put methods while holding a spinlock 2006-09-25 21:08:40 -07:00
kobject_uevent.c Driver core: accept all valid action-strings in uevent-trigger 2007-07-18 15:49:49 -07:00
kobject.c sysfs: make kobj point to sysfs_dirent instead of dentry 2007-07-11 16:09:08 -07:00
kref.c kref: fix CPU ordering with respect to krefs 2007-04-27 10:57:29 -07:00
libcrc32c.c
list_debug.c [PATCH] More list debugging context 2006-12-07 08:39:35 -08:00
locking-selftest-hardirq.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-mutex.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-rlock-hardirq.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-rlock-softirq.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-rlock.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-rsem.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-softirq.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-spin-hardirq.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-spin-softirq.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-spin.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-wlock-hardirq.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-wlock-softirq.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-wlock.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest-wsem.h [PATCH] lockdep: locking API self tests 2006-07-03 15:27:03 -07:00
locking-selftest.c [PATCH] lockdep: show more details about self-test failures 2006-12-07 08:39:43 -08:00
Makefile add argv_split() 2007-07-18 08:47:40 -07:00
parser.c [AFS]: Make the match_*() functions take const options. 2007-05-03 03:10:39 -07:00
percpu_counter.c percpu_counters: use for_each_online_cpu() 2007-07-16 09:05:41 -07:00
plist.c
prio_tree.c
radix-tree.c [LIB]: export radix_tree_preload() 2007-07-14 16:05:04 +10:00
random32.c [PATCH] severing module.h->sched.h 2006-12-04 02:00:22 -05:00
rbtree.c [PATCH] rbtree: fixed reversed RB_EMPTY_NODE and rb_next/prev 2006-09-30 20:26:56 +02:00
reciprocal_div.c [PATCH] SLAB: use a multiply instead of a divide in obj_to_index() 2006-12-13 09:05:49 -08:00
rwsem-spinlock.c Lockdep: add lockdep_set_class_and_subclass() and lockdep_set_subclass() 2006-10-11 01:45:14 -04:00
rwsem.c Lockdep: add lockdep_set_class_and_subclass() and lockdep_set_subclass() 2006-10-11 01:45:14 -04:00
semaphore-sleepers.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
sha1.c [PATCH] Numerous fixes to kernel-doc info in source files. 2007-02-11 10:51:32 -08:00
smp_processor_id.c
sort.c [PATCH] Numerous fixes to kernel-doc info in source files. 2007-02-11 10:51:32 -08:00
spinlock_debug.c [PATCH] x86: all cpu backtrace 2006-12-07 02:14:01 +01:00
string.c [STRING]: Move strcasecmp/strncasecmp to lib/string.c 2007-04-26 01:54:39 -07:00
swiotlb.c fix section mismatch warning in lib/swiotlb.c 2007-05-08 11:14:59 -07:00
textsearch.c Various typo fixes. 2007-02-17 19:07:33 +01:00
ts_bm.c [TEXTSEARCH]: Fix Boyer Moore initialization bug 2006-08-22 14:33:58 -07:00
ts_fsm.c [PATCH] lib/ts_fsm.c: constify structs 2006-09-29 09:18:23 -07:00
ts_kmp.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
vsprintf.c vsprintf.c: optimizing, part 2: base 10 conversion speedup, v2 2007-07-16 09:05:52 -07:00