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authorVivek Goyal <vgoyal@redhat.com>2009-12-03 12:59:50 -0500
committerJens Axboe <jens.axboe@oracle.com>2009-12-03 19:28:52 +0100
commit8682e1f15f26dae9a9e8af794d179055fbd81166 (patch)
treed6e87631f91527656490df9b28be107fb5e974b0 /block
parent220841906fccafaf4094e87bdb6d252e20cf8c7c (diff)
downloadvexpress-lsk-8682e1f15f26dae9a9e8af794d179055fbd81166.tar.gz
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>
Diffstat (limited to 'block')
-rw-r--r--block/cfq-iosched.c30
1 files changed, 20 insertions, 10 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 7d345e772d8..3a62ce95dae 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -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.