Commit Graph

24 Commits

Author SHA1 Message Date
Kip Macy
947265b6bd - track maximum wait time
- resize columns based on actual observed numerical values

MFC after:	3 days
2008-07-27 21:45:20 +00:00
Attilio Rao
90356491d7 - Embed the recursion counter for any locking primitive directly in the
lock_object, using an unified field called lo_data.
- Replace lo_type usage with the w_name usage and at init time pass the
  lock "type" directly to witness_init() from the parent lock init
  function.  Handle delayed initialization before than
  witness_initialize() is called through the witness_pendhelp structure.
- Axe out LO_ENROLLPEND as it is not really needed.  The case where the
  mutex init delayed wants to be destroyed can't happen because
  witness_destroy() checks for witness_cold and panic in case.
- In enroll(), if we cannot allocate a new object from the freelist,
  notify that to userspace through a printf().
- Modify the depart function in order to return nothing as in the current
  CVS version it always returns true and adjust callers accordingly.
- Fix the witness_addgraph() argument name prototype.
- Remove unuseful code from itismychild().

This commit leads to a shrinked struct lock_object and so smaller locks,
in particular on amd64 where 2 uintptr_t (16 bytes per-primitive) are
gained.

Reviewed by:	jhb
2008-05-15 20:10:06 +00:00
Attilio Rao
13ddf72de7 Really, no explicit checks against against lock_class_* object should be
done in consumers code: using locks properties is much more appropriate.
Fix current code doing these bogus checks.

Note: Really, callout are not usable by all !(LC_SPINLOCK | LC_SLEEPABLE)
primitives like rmlocks doesn't implement the generic lock layer
functions, but they can be equipped for this, so the check is still
valid.

Tested by: matteo, kris (earlier version)
Reviewed by: jhb
2008-02-06 00:04:09 +00:00
Kris Kennaway
357911ce77 Fix logic in skipcount handling (used to sample every 1/N lock operations
to reduce profiling overhead)
2008-01-08 01:11:40 +00:00
Jeff Roberson
0c66dc6758 - Pause a while after disabling lock profiling and before resetting it
to be sure that all participating CPUs have stopped updating it.
 - Restore the behavior of printing the name of the lock type in the output.
2007-12-31 03:45:51 +00:00
Jeff Roberson
eea4f254fe - Re-implement lock profiling in such a way that it no longer breaks
the ABI when enabled.  There is no longer an embedded lock_profile_object
   in each lock.  Instead a list of lock_profile_objects is kept per-thread
   for each lock it may own.  The cnt_hold statistic is now always 0 to
   facilitate this.
 - Support shared locking by tracking individual lock instances and
   statistics in the per-thread per-instance lock_profile_object.
 - Make the lock profiling hash table a per-cpu singly linked list with a
   per-cpu static lock_prof allocator.  This removes the need for an array
   of spinlocks and reduces cache contention between cores.
 - Use a seperate hash for spinlocks and other locks so that only a
   critical_enter() is required and not a spinlock_enter() to modify the
   per-cpu tables.
 - Count time spent spinning in the lock statistics.
 - Remove the LOCK_PROFILE_SHARED option as it is always supported now.
 - Specifically drop and release the scheduler locks in both schedulers
   since we track owners now.

In collaboration with:	Kip Macy
Sponsored by:	Nokia
2007-12-15 23:13:31 +00:00
Stephan Uphoff
f53d15fe1b Initial checkin for rmlock (read mostly lock) a multi reader single writer
lock optimized for almost exclusive reader access. (see also rmlock.9)

TODO:
    Convert to per cpu variables linkerset as soon as it is available.
    Optimize UP (single processor)  case.
2007-11-08 14:47:55 +00:00
Attilio Rao
4486adc51f Currently the LO_NOPROFILE flag (which is masked on upper level code by
per-primitive macros like MTX_NOPROFILE, SX_NOPROFILE or RW_NOPROFILE) is
not really honoured. In particular lock_profile_obtain_lock_failure() and
lock_profile_obtain_lock_success() are naked respect this flag.
The bug leads to locks marked with no-profiling to be profiled as well.
In the case of the clock_lock, used by the timer i8254 this leads to
unpredictable behaviour both on amd64 and ia32 (double faults panic,
sudden reboots, etc.). The amd64 clock_lock is also not marked as
not profilable as it should be.
Fix these bugs adding proper checks in the lock profiling code and at
clock_lock initialization time.

i8254 bug pointed out by: kris
Tested by: matteo, Giuseppe Cocomazzi <sbudella at libero dot it>
Approved by: jeff (mentor)
Approved by: re
2007-09-14 01:12:39 +00:00
Kris Kennaway
cdcc788a7e Revert some debugging KTRs that were added during development. 2007-06-03 18:24:31 +00:00
John Baldwin
c91fcee75d Move lock_profile_object_{init,destroy}() into lock_{init,destroy}(). 2007-05-18 15:04:59 +00:00
Kip Macy
8289600ce7 skip call to _lock_profile_obtain_lock_success entirely if acquisition time is non-zero
(i.e. recursing or adding sharers)
2007-04-03 18:36:27 +00:00
Kip Macy
fe68a91631 general LOCK_PROFILING cleanup
- only collect timestamps when a lock is contested - this reduces the overhead
  of collecting profiles from 20x to 5x

- remove unused function from subr_lock.c

- generalize cnt_hold and cnt_lock statistics to be kept for all locks

- NOTE: rwlock profiling generates invalid statistics (and most likely always has)
  someone familiar with that should review
2007-02-26 08:26:44 +00:00
Kip Macy
aa077979f6 Bug fix for obscenely large wait times on uncontested locks
if waittime was zero (the lock was uncontested) l->lpo_waittime
in the hash table would not get initialized.

Inspection prompted by questions from: Attilio Rao
2006-12-04 22:15:50 +00:00
Kip Macy
61bd5e21b3 track lock class name in a way that doesn't break WITNESS 2006-11-13 05:41:46 +00:00
Kip Macy
44a96b46bd Unbreak witness 2006-11-12 23:23:38 +00:00
Kip Macy
54e57f7613 show lock class in profiling output for default case where type is not specified when initializing the lock
Approved by: scottl (standing in for mentor rwatson)
2006-11-12 03:30:01 +00:00
Kip Macy
ed6a7c42f6 tinderbox fix 2006-11-11 07:38:48 +00:00
Kip Macy
cf2c39e7a2 remove lingering call to rd(tick) 2006-11-11 07:28:45 +00:00
Kip Macy
83b72e3e25 missed nits replacing mutex with lock 2006-11-11 06:28:47 +00:00
Kip Macy
7c0435b933 MUTEX_PROFILING has been generalized to LOCK_PROFILING. We now profile
wait (time waited to acquire) and hold times for *all* kernel locks. If
the architecture has a system synchronized TSC, the profiling code will
use that - thereby minimizing profiling overhead. Large chunks of profiling
code have been moved out of line, the overhead measured on the T1 for when
it is compiled in but not enabled is < 1%.

Approved by: scottl (standing in for mentor rwatson)
Reviewed by: des and jhb
2006-11-11 03:18:07 +00:00
John Baldwin
3f08bd8bce Add a basic reader/writer lock implementation to the kernel. This
implementation is by no means perfect as far as some of the algorithms
that it uses and the fact that it is missing some functionality (try
locks and upgrades/downgrades are not there yet), however it does seem
to work in my local testing.  There is more detail in the comments in the
code, but the short version follows.

A reader/writer lock is very much like a regular mutex: it cannot be held
across a voluntary sleep; it can be acquired in an interrupt thread; if
the lock is held by a writer then the priority of any threads that block
on the lock will be lent to the owner; the simple case lock operations all
are done in a single atomic op.  It also shares some similiarities
with sx locks: it supports reader/writer semantics (multiple readers,
but single writers); readers are allowed to recurse, but writers are not.

We can extend this implementation further by either improving algorithms
or adding new functionality, but this should at least give us a base to
work with now.

Reviewed by:	arch (in theory)
Tested on:	i386 (4 cpu box with a kernel module that used 4 threads
		that randomly chose between read locks and write locks
		that ran w/o panicing for over a day solid.  It usually
		panic'd within a few seconds when there were bugs during
		testing. :)  The kernel module source is available on
		request.)
2006-01-27 23:13:26 +00:00
John Baldwin
25e498b4b0 Always include the lock_classes[] array in the kernel. The
"is it a spinlock" test in mtx_destroy() needs it even in non-debug
kernels.

Reported by:	danfe
2006-01-18 18:02:50 +00:00
John Baldwin
6ef970a972 Bah. Fix 'show lock' to actually be compiled in. I had just fixed this in
p4 but had an older subr_lock.c on the machine I committed to CVS from.
2006-01-17 16:58:32 +00:00
John Baldwin
83a81bcb14 Add a new file (kern/subr_lock.c) for holding code related to struct
lock_obj objects:
- Add new lock_init() and lock_destroy() functions to setup and teardown
  lock_object objects including KTR logging and registering with WITNESS.
- Move all the handling of LO_INITIALIZED out of witness and the various
  lock init functions into lock_init() and lock_destroy().
- Remove the constants for static indices into the lock_classes[] array
  and change the code outside of subr_lock.c to use LOCK_CLASS to compare
  against a known lock class.
- Move the 'show lock' ddb function and lock_classes[] array out of
  kern_mutex.c over to subr_lock.c.
2006-01-17 16:55:17 +00:00