On Tue, Sep 10, 2013 at 10:31:54AM +0100, Mel Gorman wrote:
> @@ -860,9 +908,14 @@ void task_numa_fault(int node, int pages, bool migrated)
> * If pages are properly placed (did not migrate) then scan slower.
> * This is reset periodically in case of phase changes
> */
> - if (!migrated)
> - p->numa_scan_period = min(sysctl_numa_balancing_scan_period_max,
> + if (!migrated) {
> + /* Initialise if necessary */
> + if (!p->numa_scan_period_max)
> + p->numa_scan_period_max = task_scan_max(p);
> +
> + p->numa_scan_period = min(p->numa_scan_period_max,
> p->numa_scan_period + jiffies_to_msecs(10));
So the next patch changes the jiffies_to_msec() thing.. is that really
worth a whole separate patch?
Also, I really don't believe any of that is 'right', increasing the scan
period by a fixed amount for every !migrated page is just wrong.
Firstly; there's the migration throttle which basically guarantees that
most pages aren't migrated -- even when they ought to be, thus inflating
the period.
Secondly; assume a _huge_ process, so large that even a small fraction
of non-migrated pages will completely clip the scan period.
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