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move VM setBound to the plugin
[simgrid.git]
/
src
/
plugins
/
vm
/
s4u_VirtualMachine.cpp
diff --git
a/src/plugins/vm/s4u_VirtualMachine.cpp
b/src/plugins/vm/s4u_VirtualMachine.cpp
index
e4f8a46
..
8bda7e7
100644
(file)
--- a/
src/plugins/vm/s4u_VirtualMachine.cpp
+++ b/
src/plugins/vm/s4u_VirtualMachine.cpp
@@
-128,7
+128,36
@@
void VirtualMachine::setRamsize(size_t ramsize)
{
pimpl_vm_->setRamsize(ramsize);
}
-
+/** @brief Set a CPU bound for a given VM.
+ * @ingroup msg_VMs
+ *
+ * 1. Note that in some cases MSG_task_set_bound() may not intuitively work for VMs.
+ *
+ * For example,
+ * On PM0, there are Task1 and VM0.
+ * On VM0, there is Task2.
+ * Now we bound 75% to Task1\@PM0 and bound 25% to Task2\@VM0.
+ * Then,
+ * Task1\@PM0 gets 50%.
+ * Task2\@VM0 gets 25%.
+ * This is NOT 75% for Task1\@PM0 and 25% for Task2\@VM0, respectively.
+ *
+ * This is because a VM has the dummy CPU action in the PM layer. Putting a task on the VM does not affect the bound of
+ * the dummy CPU action. The bound of the dummy CPU action is unlimited.
+ *
+ * There are some solutions for this problem. One option is to update the bound of the dummy CPU action automatically.
+ * It should be the sum of all tasks on the VM. But, this solution might be costly, because we have to scan all tasks
+ * on the VM in share_resource() or we have to trap both the start and end of task execution.
+ *
+ * The current solution is to use setBound(), which allows us to directly set the bound of the dummy CPU action.
+ *
+ * 2. Note that bound == 0 means no bound (i.e., unlimited). But, if a host has multiple CPU cores, the CPU share of a
+ * computation task (or a VM) never exceeds the capacity of a CPU core.
+ */
+void VirtualMachine::setBound(double bound)
+{
+ simgrid::simix::kernelImmediate([this, bound]() { pimpl_vm_->setBound(bound); });
+}
/** @brief Retrieve a copy of the parameters of that VM/PM
* @details The ramsize and overcommit fields are used on the PM too */
void VirtualMachine::getParameters(vm_params_t params)