linux/kernel/lockdep.c, branch v2.6.23

lockdep debugging: give stacktrace for init_error

2007-07-19T17:04:49Z

When I started adding support for lockdep to 64-bit powerpc, I got a lockdep_init_error and with this patch was able to pinpoint why and where to put lockdep_init(). Let's support this generally for others adding lockdep support to their architecture. Signed-off-by: Johannes Berg Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Arjan van de Ven Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lockstat: measure lock bouncing

2007-07-19T17:04:49Z

__acquire | lock _____ | \ | __contended | | | wait | _______/ |/ | __acquired | __release | unlock We measure acquisition and contention bouncing. This is done by recording a cpu stamp in each lock instance. Contention bouncing requires the cpu stamp to be set on acquisition. Hence we move __acquired into the generic path. __acquired is then used to measure acquisition bouncing by comparing the current cpu with the old stamp before replacing it. __contended is used to measure contention bouncing (only useful for preemptable locks) [akpm@linux-foundation.org: cleanups] Signed-off-by: Peter Zijlstra Acked-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lockdep: various fixes

2007-07-19T17:04:49Z

- update the copyright notices - use the default hash function - fix a thinko in a BUILD_BUG_ON - add a WARN_ON to spot inconsitent naming - fix a termination issue in /proc/lock_stat [akpm@linux-foundation.org: cleanups] Signed-off-by: Peter Zijlstra Acked-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lockstat: human readability tweaks

2007-07-19T17:04:49Z

Present all this fancy new lock statistics information: *warning, _wide_ output ahead* (output edited for purpose of brevity) # cat /proc/lock_stat lock_stat version 0.1 ----------------------------------------------------------------------------------------------------------------------------------------------------------------- class name contentions waittime-min waittime-max waittime-total acquisitions holdtime-min holdtime-max holdtime-total ----------------------------------------------------------------------------------------------------------------------------------------------------------------- &inode->i_mutex: 14458 6.57 398832.75 2469412.23 6768876 0.34 11398383.65 339410830.89 --------------- &inode->i_mutex 4486 [] pipe_wait+0x86/0x8d &inode->i_mutex 0 [] pipe_write_fasync+0x29/0x5d &inode->i_mutex 0 [] pipe_read+0x74/0x3a5 &inode->i_mutex 0 [] do_lookup+0x81/0x1ae ................................................................................................................................................................. &inode->i_data.tree_lock-W: 491 0.27 62.47 493.89 2477833 0.39 468.89 1146584.25 &inode->i_data.tree_lock-R: 65 0.44 4.27 48.78 26288792 0.36 184.62 10197458.24 -------------------------- &inode->i_data.tree_lock 46 [] __do_page_cache_readahead+0x69/0x24f &inode->i_data.tree_lock 31 [] add_to_page_cache+0x31/0xba &inode->i_data.tree_lock 0 [] __do_page_cache_readahead+0xc2/0x24f &inode->i_data.tree_lock 0 [] find_get_page+0x1a/0x58 ................................................................................................................................................................. proc_inum_idr.lock: 0 0.00 0.00 0.00 36 0.00 65.60 148.26 proc_subdir_lock: 0 0.00 0.00 0.00 3049859 0.00 106.81 1563212.42 shrinker_rwsem-W: 0 0.00 0.00 0.00 5 0.00 1.73 3.68 shrinker_rwsem-R: 0 0.00 0.00 0.00 633 2.57 246.57 10909.76 'contentions' and 'acquisitions' are the number of such events measured (since the last reset). The waittime- and holdtime- (min, max, total) numbers are presented in microseconds. If there are any contention points, the lock class is presented in the block format (as i_mutex and tree_lock above), otherwise a single line of output is presented. The output is sorted on absolute number of contentions (read + write), this should get the worst offenders presented first, so that: # grep : /proc/lock_stat | head will quickly show who's bad. The stats can be reset using: # echo 0 > /proc/lock_stat [bunk@stusta.de: make 2 functions static] [akpm@linux-foundation.org: fix printk warning] Signed-off-by: Peter Zijlstra Acked-by: Ingo Molnar Acked-by: Jason Baron Signed-off-by: Adrian Bunk 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

lockdep: reduce the ifdeffery

2007-07-19T17:04:49Z

Move code around to get fewer but larger #ifdef sections. Break some in-function #ifdefs out into their own functions. Signed-off-by: Peter Zijlstra Acked-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lockdep: sanitise CONFIG_PROVE_LOCKING

2007-07-19T17:04:49Z

Ensure that all of the lock dependency tracking code is under CONFIG_PROVE_LOCKING. This allows us to use the held lock tracking code for other purposes. Signed-off-by: Peter Zijlstra Acked-by: Ingo Molnar Acked-by: Jason Baron Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kallsyms: make KSYM_NAME_LEN include space for trailing '\0'

2007-07-17T17:23:03Z

KSYM_NAME_LEN is peculiar in that it does not include the space for the trailing '\0', forcing all users to use KSYM_NAME_LEN + 1 when allocating buffer. This is nonsense and error-prone. Moreover, when the caller forgets that it's very likely to subtly bite back by corrupting the stack because the last position of the buffer is always cleared to zero. This patch increments KSYM_NAME_LEN by one and updates code accordingly. * off-by-one bug in asm-powerpc/kprobes.h::kprobe_lookup_name() macro is fixed. * Where MODULE_NAME_LEN and KSYM_NAME_LEN were used together, MODULE_NAME_LEN was treated as if it didn't include space for the trailing '\0'. Fix it. Signed-off-by: Tejun Heo Acked-by: Paulo Marques Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lockdep: removed unused ip argument in mark_lock & mark_held_locks

2007-05-08T18:15:13Z

It looks like a remainder from designing... Signed-off-by: Jarek Poplawski Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

lockdep: lookup_chain_cache comment errata

2007-05-08T18:15:11Z

Signed-off-by: Jarek Poplawski Acked-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds