X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/75587e6a0a5f0dd8356a90b67578a3be37d134de..b556a0d912f836b6a661d7d1e1617f9d949e9f98:/src/msg/msg_task.c

diff --git a/src/msg/msg_task.c b/src/msg/msg_task.c
index d751912436..f995d10d64 100644
--- a/src/msg/msg_task.c
+++ b/src/msg/msg_task.c
@@ -475,7 +475,34 @@ void MSG_task_set_bound(msg_task_t task, double bound)
  *
  * \param task a target task
  * \param host the host having a multi-core CPU
- * \param mask the value specifying the CPU affinity setting of the task
+ * \param mask the bit mask of a new CPU affinity setting for the task
+ *
+ *
+ * Usage:
+ * 0. Define a host with multiple cores.
+ *    <host id="PM0" power="1E8" core="2"/>
+ *
+ * 1. Pin a given task to the first CPU core of a host.
+ *   MSG_task_set_affinity(task, pm0, 0x01);
+ *
+ * 2. Pin a given task to the third CPU core of a host. Turn on the third bit of the mask.
+ *   MSG_task_set_affinity(task, pm0, 0x04); // 0x04 == 100B
+ *
+ * 3. Pin a given VM to the first CPU core of a host.
+ *   MSG_vm_set_affinity(vm, pm0, 0x01);
+ *
+ * See examples/msg/cloud/multicore.c for more information.
+ *
+ *
+ * Note:
+ * 1. The current code does not allow an affinity of a task to multiple cores.
+ * The mask value 0x03 (i.e., a given task will be executed on the first core
+ * or the second core) is not allowed. The mask value 0x01 or 0x02 works. See
+ * cpu_cas01.c for details.
+ *
+ * 2. It is recommended to first compare simulation results in both the Lazy
+ * and Full calculation modes (using --cfg=cpu/optim:Full or not). Fix
+ * cpu_cas01.c if you find wrong results in the Lazy mode.
  *
  */
 void MSG_task_set_affinity(msg_task_t task, msg_host_t host, unsigned long mask)