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    SubjectRe: [PATCH 11/23] io-controller: Introduce group idling
    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@redhat.com>

    Acked-by: Rik van Riel <riel@redhat.com>

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