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blkio: Provide some isolation between groups 

o Do not allow following three operations across groups for isolation.
	- selection of co-operating queues
	- preemtpions across groups
	- request merging across groups.

o Async queues are currently global and not per group. Allow preemption of
  an async queue if a sync queue in other group gets backlogged.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
hifive-unleashed-5.1
Vivek Goyal 2009-12-03 12:59:50 -05:00 committed by Jens Axboe
parent 220841906f
commit 8682e1f15f
1 changed files with 20 additions and 10 deletions
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30
block/cfq-iosched.c
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@ -1461,6 +1461,9 @@ static int cfq_allow_merge(struct request_queue *q, struct request *rq,
struct cfq_io_context *cic;
struct cfq_queue *cfqq;
/* Deny merge if bio and rq don't belong to same cfq group */
if ((RQ_CFQQ(rq))->cfqg != cfq_get_cfqg(cfqd, 0))
return false;
/*
* Disallow merge of a sync bio into an async request.
*/
@ -1698,6 +1701,10 @@ static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
if (!cfqq)
return NULL;
/* If new queue belongs to different cfq_group, don't choose it */
if (cur_cfqq->cfqg != cfqq->cfqg)
return NULL;
/*
* It only makes sense to merge sync queues.
*/
@ -2950,22 +2957,12 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
if (!cfqq)
return false;
if (cfq_slice_used(cfqq))
return true;
if (cfq_class_idle(new_cfqq))
return false;
if (cfq_class_idle(cfqq))
return true;
/* Allow preemption only if we are idling on sync-noidle tree */
if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
new_cfqq->service_tree->count == 2 &&
RB_EMPTY_ROOT(&cfqq->sort_list))
return true;
/*
* if the new request is sync, but the currently running queue is
* not, let the sync request have priority.
@ -2973,6 +2970,19 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
return true;
if (new_cfqq->cfqg != cfqq->cfqg)
return false;
if (cfq_slice_used(cfqq))
return true;
/* Allow preemption only if we are idling on sync-noidle tree */
if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
new_cfqq->service_tree->count == 2 &&
RB_EMPTY_ROOT(&cfqq->sort_list))
return true;
/*
* So both queues are sync. Let the new request get disk time if
* it's a metadata request and the current queue is doing regular IO.