Changes between Version 1 and Version 2 of user_synchro

Timestamp:

Oct 9, 2018, 12:23:32 PM (6 years ago)

Author:

alain

Comment:

--

user_synchro

@@ -9 +9 @@
 == B) Mutex ==
 
- This file defines an user level POSIX compliant mutex.
- *
- * It can be used by muti-threaded user applications to synchronise user threads
- * running in different clusters.
- *
- * A mutex is declared by a given user process as a "pthread_mutex_t" global variable.
- * This user type is implemented as an unsigned long, but the value is not used by the 
- * kernel. ALMOS-MKH uses only the mutex virtual address as an identifier.
- * For each user mutex, ALMOS-MKH creates a kernel "remote_mutex_t" structure,
- * dynamically allocated in the reference cluster by the remote_mutex_create() function, 
- * and destroyed by the remote_mutex_destroy() function, using RPC if the calling thread
- * is not running in the reference cluster. 
- *
- * The blocking "remote_mutex_lock()" function implements a descheduling policy when
- * the lock is already taken by another thread : the calling thread is registered 
- * in a waiting queue, rooted in the mutex structure, and the the calling thread 
- * is blocked on the THREAD_BLOCKED_MUTEX condition. 
- * The "remote_mutex_unlock()" function unblocks the first waiting thread in the queue
- * without releasing the mutex if queue is not empty.
+The user level, POSIX compliant, mutex API is defined in the '''pthread''' library implemented by the [https://www-soc.lip6.fr/trac/almos-mkh/browser/trunk/libs/libpthread/pthread.h pthread.h] and [https://www-soc.lip6.fr/trac/almos-mkh/browser/trunk/libs/libpthread/pthread.c pthread.c] files.
+
+It can be used by muti-threaded user applications to synchronise user threads running in different clusters.
+
+A mutex is declared by a given user process as a ''pthread_mutex_t'' global variable. This user type is implemented by ALMOS-MKH as an ''unsigned long'', but the value stored in user space is NOT used by the kernel. ALMOS-MKH uses only the mutex virtual address as an identifier for the mutex.
+
+The kernel implementation of a mutex is defined in the [https://www-soc.lip6.fr/trac/almos-mkh/browser/trunk/kernel/libk/remote_mutex.h remote_mutex.h] and [https://www-soc.lip6.fr/trac/almos-mkh/browser/trunk/kernel/libk/remote_mutex.c remote_mutex.c] files.
+
+For each user mutex, ALMOS-MKH creates a kernel ''remote_mutex_t'' structure, dynamically allocated in the reference cluster (i.e. in the cluster containing the reference process descriptor) by the '''remote_mutex_create()''' function, and destroyed by the '''remote_mutex_destroy()''' function, using RPC if the calling thread is not running in the reference cluster. The blocking '''remote_mutex_lock()''' function implements a descheduling policy when the lock is already taken by another thread : the calling thread is registered in a waiting queue, rooted in the ''remote_mutex_t'' structure, and the the calling thread is blocked on the THREAD_BLOCKED_MUTEX condition. The '''remote_mutex_unlock()''' function unblocks the first waiting thread in the queue without releasing the mutex if the queue is not empty.
+
 
 == C) Condvar ==