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authorShaohua Li writes <shaohua.li@intel.com>2010-12-13 14:32:22 +0100
committerJens Axboe <jaxboe@fusionio.com>2010-12-13 14:32:22 +0100
commite4ea0c16a85d221ebcc3a21f32e321440459e0fc (patch)
tree47acf4da84f9a448e6eb6172a5440ccc60696ed9 /block
parent760701bfe14faee8ea0608a9cab2046071d98a39 (diff)
downloadlinux-e4ea0c16a85d221ebcc3a21f32e321440459e0fc.tar.gz
block cfq: select new workload if priority changed
If priority is changed, continuing to check workload_expires and service tree
count of the previous workload does not make sense. We should always choose
the workload with lowest key of new priority in such case.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'block')
-rw-r--r--block/cfq-iosched.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 5d0349d602fe..9b186fd6bf47 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -2101,6 +2101,7 @@ static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
 	unsigned count;
 	struct cfq_rb_root *st;
 	unsigned group_slice;
+	enum wl_prio_t original_prio = cfqd->serving_prio;
 
 	if (!cfqg) {
 		cfqd->serving_prio = IDLE_WORKLOAD;
@@ -2119,6 +2120,9 @@ static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
 		return;
 	}
 
+	if (original_prio != cfqd->serving_prio)
+		goto new_workload;
+
 	/*
 	 * For RT and BE, we have to choose also the type
 	 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
@@ -2133,6 +2137,7 @@ static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
 	if (count && !time_after(jiffies, cfqd->workload_expires))
 		return;
 
+new_workload:
 	/* otherwise select new workload type */
 	cfqd->serving_type =
 		cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);