On 01/25/2017 09:30 AM, Mel Gorman wrote: > As suggested by Vlastimil Babka and Tejun Heo, this patch uses a static > work_struct to co-ordinate the draining of per-cpu pages on the workqueue. > Only one task can drain at a time but this is better than the previous > scheme that allowed multiple tasks to send IPIs at a time. > > One consideration is whether parallel requests should synchronise against > each other. This patch does not synchronise for a global drain as the common > case for such callers is expected to be multiple parallel direct reclaimers > competing for pages when the watermark is close to min. Draining the per-cpu > list is unlikely to make much progress and serialising the drain is of > dubious merit. Drains are synchonrised for callers such as memory hotplug > and CMA that care about the drain being complete when the function returns. > > Signed-off-by: Mel Gorman <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
