On 12/02/2012 01:43 PM, Ingo Molnar wrote:
This is not entirely correct as this task might have scheduled or
migrate ther - but statistically there will be correlation to the
^^^^ there?
tasks that we share memory with, and correlation is all we need.
We map out the relation itself by filtering out the highest address
ask that is below our own task address, per working set scan
^^^ task?
iteration.
@@ -906,23 +945,122 @@ out_backoff:
}
/*
+ * Track our "memory buddies" the tasks we actively share memory with.
+ *
+ * Firstly we establish the identity of some other task that we are
+ * sharing memory with by looking at rq[page::last_cpu].curr - i.e.
+ * we check the task that is running on that CPU right now.
+ *
+ * This is not entirely correct as this task might have scheduled or
+ * migrate ther - but statistically there will be correlation to the
^^^^ there
+ * tasks that we share memory with, and correlation is all we need.
+ *
+ * We map out the relation itself by filtering out the highest address
+ * ask that is below our own task address, per working set scan
^^^ task?
If that word is "task", the comment makes sense. If it is
something else, I'm back to square one on what the code does :)
void task_numa_fault(int node, int last_cpu, int pages)
{
struct task_struct *p = current;
int priv = (task_cpu(p) == last_cpu);
+ int idx = 2*node + priv;
if (unlikely(!p->numa_faults)) {
- int size = sizeof(*p->numa_faults) * 2 * nr_node_ids;
+ int entries = 2*nr_node_ids;
+ int size = sizeof(*p->numa_faults) * entries;
- p->numa_faults = kzalloc(size, GFP_KERNEL);
+ p->numa_faults = kzalloc(2*size, GFP_KERNEL);
So we multiply nr_node_ids by 2. Twice.
That kind of magic deserves a comment explaining how
and why. How about:
/*
* We track two arrays with private and shared faults
* for each NUMA node. The p->numa_faults_curr array
* is allocated at the same time as the p->numa_faults
* array.
*/
int size = sizeof(*p->numa_faults) * 4 * nr_node_ids;
if (!p->numa_faults)
return;
+ /*
+ * For efficiency reasons we allocate ->numa_faults[]
+ * and ->numa_faults_curr[] at once and split the
+ * buffer we get. They are separate otherwise.
+ */
+ p->numa_faults_curr = p->numa_faults + entries;
}
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>