Changes between Initial Version and Version 1 of library_locks

Timestamp:

Aug 5, 2014, 2:08:01 PM (11 years ago)

Author:

alain

Comment:

--

library_locks

@@ +1 @@
+= The spin_lock library =
+
+The [source:soft/giet_vm/giet_libs/spin_lock.c spin_lock.c] and [source:soft/giet_vm/giet_libs/spin_lock.h spin_lock.h] 
+files define a user-level spin-lock service to obtain exclusive access to a shared resource in a parallel multi-tasks application.
+Each lock (giet_lock_t object) occupies a complete 64 bytes cache line to avoid false sharing.
+If the hardware architecture supports hardware cache coherence, it is recommanded to store the lock in a cachable segment architecture
+
+ == Lock declaration ==
+
+There is to ways to define a user-level lock, depending on the placement constraints:
+
+ * If the lock is defined as a global variable in the application code, there is no precise control on the lock placement: the lock will be stored in the application global data ''vseg".
+
+ * If the lock is defined as a specific ''vobj'' in the application mapping, it will be stored in the ''vseg'' specified in the mapping. The lock should not be declared as a global variable in the application code, and the lock virtual address can be obtained using the ''giet_vobj_get_vbase() system call.
+
+ == Access functions ==
+
+ * '''void lock_acquire( giet_lock_t * lock )'''
+This blocking function uses an atomic LL/SC mechanism to take the lock, and return only when the lock has been successfully taken.
+
+ * '''void lock_release( giet_lock_t * lock )'''
+This function uses a simple SW to release the lock.