Messages in this thread Patch in this message | | | Subject | [PATCH] cfq-iosched: allow groups preemption for sync-noidle workloads | From | Konstantin Khlebnikov <> | Date | Thu, 23 Jun 2011 20:21:59 +0400 |
| |
commit v2.6.32-102-g8682e1f "blkio: Provide some isolation between groups" break fast switching between task and journal-thread for very common write-fsync workload. cfq wait idle slice at each cfqq switch, if this task is from non-root blkio cgroup.
This patch move idling sync-noidle preempting check little bit upwards and update new service_tree->count check for case with two different groups. I do not quite understand what means these check for new_cfqq, but now it even works.
Without patch I got 49 iops and with this patch 798, for this trivial fio script:
[write-fsync] cgroup=test cgroup_weight=1000 rw=write fsync=1 size=100m runtime=10s
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> --- block/cfq-iosched.c | 14 +++++++------- 1 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 3c7b537..c71533e 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -3318,19 +3318,19 @@ 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 && + new_cfqq->service_tree->count == 1+(new_cfqq->cfqg == cfqq->cfqg) && RB_EMPTY_ROOT(&cfqq->sort_list)) return true; + if (new_cfqq->cfqg != cfqq->cfqg) + return false; + + if (cfq_slice_used(cfqq)) + 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.
| |