Con Kolivas wrote:
On Sunday 18 June 2006 18:26, Peter Williams wrote:
3. Thanks to suggestions from Con Kolivas with respect to alternative
methods to reduce the possibility of a task being starved of CPU while
holding an important system resource, enforcement of caps is now
quite strict. However, there will still be occasions where caps may be
exceeded due to this mechanism vetoing enforcement.
I hate to do this to you again but the mutexes held count advice I gave was
slightly off :|
int fastcall __sched mutex_lock_interruptible(struct mutex *lock)
{
+ int ret;
+
might_sleep();
- return __mutex_fastpath_lock_retval
+ ret = __mutex_fastpath_lock_retval
(&lock->count, __mutex_lock_interruptible_slowpath);
+
+ if (!ret)
+ inc_mutex_count();
+
+ return ret;
}
EXPORT_SYMBOL(mutex_lock_interruptible);
@@ -357,8 +381,13 @@ static inline int __mutex_trylock_slowpa
*/
int fastcall __sched mutex_trylock(struct mutex *lock)
{
- return __mutex_fastpath_trylock(&lock->count,
+ int ret = __mutex_fastpath_trylock(&lock->count,
__mutex_trylock_slowpath);
+
+ if (!ret)
+ inc_mutex_count();
+
+ return ret;
See my track-mutexes-1.patch I recently posted.
int fastcall __sched mutex_lock_interruptible(struct mutex *lock)
{
+ int ret;
+
might_sleep();
- return __mutex_fastpath_lock_retval
+ ret = __mutex_fastpath_lock_retval
(&lock->count, __mutex_lock_interruptible_slowpath);
+ if (likely(!ret))
+ inc_mutex_count();
+ return ret;
}
EXPORT_SYMBOL(mutex_lock_interruptible);
@@ -308,8 +325,12 @@ static inline int __mutex_trylock_slowpa
*/
int fastcall mutex_trylock(struct mutex *lock)
{
- return __mutex_fastpath_trylock(&lock->count,
+ int ret = __mutex_fastpath_trylock(&lock->count,
__mutex_trylock_slowpath);
+
+ if (likely(ret))
+ inc_mutex_count();
+ return ret;
}
Note the if !ret in mutex_lock_interruptible vs the if ret in mutex_trylock(
I really should have given you the original debugging code that went with it,
sorry.
That's OK. I should have read the comments above mutex_trylock() more
carefully myself.
Thanks
Peter
PS Have you thought about merging these caps into staircase in lieu of
SCHED_IDLEPRIO? Hard caps should be easy and soft caps not much harder.
If that was available I could merge the caps patch with plugsched.
--
Peter Williams [email protected]
"Learning, n. The kind of ignorance distinguishing the studious."
-- Ambrose Bierce
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