From 8682e1f15f26dae9a9e8af794d179055fbd81166 Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Thu, 3 Dec 2009 12:59:50 -0500 Subject: [PATCH] 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 Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 30 ++++++++++++++++++++---------- 1 file changed, 20 insertions(+), 10 deletions(-) diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 7d345e772d88..3a62ce95daec 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. -- 2.34.1