Hello Rik
On Fri, Sep 13, 2013 at 9:41 AM, Rik van Riel <riel@xxxxxxxxxx> wrote:
> On 09/12/2013 08:45 PM, Hillf Danton wrote:
>> If a page monitored by ANB is migrated, its footprint should be erased from
>> numa-hint-fault account, because it is no longer used. Or two pages, the
>> migrated page and its target page, are used in the view of task placement.
>>
>>
>> Signed-off-by: Hillf Danton <dhillf@xxxxxxxxx>
>
> NAK
>
> The numa faults buffer contains the number of pages on each
> node that the task recently faulted on.
>
> If the page got migrated, it is only counted on the new node,
> not on the old one. That means there is no need to subtract
> it on the old node.
>
Yes, I cut at wrong place.
Since old node is valid, the footprint of migrated page already
deposits in ->numa_faults, and cut should go there.
Thanks
Hillf
--- a/kernel/sched/fair.c Wed Sep 11 18:33:00 2013
+++ b/kernel/sched/fair.c Fri Sep 13 14:10:34 2013
@@ -1560,6 +1560,23 @@ void task_numa_fault(int last_cpupid, in
p->numa_pages_migrated += pages;
p->numa_faults_buffer[task_faults_idx(node, priv)] += pages;
+
+ if (migrated && last_cpupid != (-1 & LAST_CPUPID_MASK)) {
+ /* Erase footprint of migrated page */
+ int idx;
+
+ idx = cpupid_to_cpu(last_cpupid);
+ idx = cpu_to_node(idx);
+ idx = task_faults_idx(idx, priv);
+
+ if (pages > 1)
+ pages >>= 1;
+
+ if (p->numa_faults[idx] >= pages)
+ p->numa_faults[idx] -= pages;
+ else if (p->numa_faults[idx])
+ p->numa_faults[idx] = 0;
+ }
}
static void reset_ptenuma_scan(struct task_struct *p)
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