Vivek Goyal wrote:
o It is not always that IO from a process or group is continuous. There are cases of dependent reads where next read is not issued till previous read has finished. For such cases, CFQ introduced the notion of slice_idle, where we idle on the queue for sometime hoping next request will come and that's how fairness is provided otherwise queue will be deleted immediately from the service tree and this process will not get the fair share. o This patch introduces the similar concept at group level. Idle on the group for a period of "group_idle" which is tunable through sysfs interface. So if a group is empty and about to be deleted, we idle for the next request. o This patch also introduces the notion of wait busy where we wait for one extra group_idle period even if queue has consumed its time slice. The reason being that group will loose its share upon removal from service tree as some other entity will be picked for dispatch and vtime jump will take place. Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxx> -- All rights reversed. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
