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authorHou Tao <houtao1@huawei.com>2017-03-01 09:02:33 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-06-14 15:05:58 +0200
commit08229c119c426fc8666f1dc2822a8c38fc77fa6a (patch)
tree7500477a188169236f92b1b67f604f8f5ad9319a /block
parent1f67d28d2707dc1da24c7f94b0a80721ea89abac (diff)
cfq-iosched: fix the delay of cfq_group's vdisktime under iops mode
commit 5be6b75610cefd1e21b98a218211922c2feb6e08 upstream. When adding a cfq_group into the cfq service tree, we use CFQ_IDLE_DELAY as the delay of cfq_group's vdisktime if there have been other cfq_groups already. When cfq is under iops mode, commit 9a7f38c42c2b ("cfq-iosched: Convert from jiffies to nanoseconds") could result in a large iops delay and lead to an abnormal io schedule delay for the added cfq_group. To fix it, we just need to revert to the old CFQ_IDLE_DELAY value: HZ / 5 when iops mode is enabled. Despite having the same value, the delay of a cfq_queue in idle class and the delay of cfq_group are different things, so I define two new macros for the delay of a cfq_group under time-slice mode and iops mode. Fixes: 9a7f38c42c2b ("cfq-iosched: Convert from jiffies to nanoseconds") Signed-off-by: Hou Tao <houtao1@huawei.com> Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'block')
-rw-r--r--block/cfq-iosched.c17
1 files changed, 15 insertions, 2 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 3ab6807773ee..c7c3d4e6bc27 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -36,9 +36,13 @@ static const u64 cfq_target_latency = (u64)NSEC_PER_SEC * 3/10; /* 300 ms */
static const int cfq_hist_divisor = 4;
/*
- * offset from end of service tree
+ * offset from end of queue service tree for idle class
*/
#define CFQ_IDLE_DELAY (NSEC_PER_SEC / 5)
+/* offset from end of group service tree under time slice mode */
+#define CFQ_SLICE_MODE_GROUP_DELAY (NSEC_PER_SEC / 5)
+/* offset from end of group service under IOPS mode */
+#define CFQ_IOPS_MODE_GROUP_DELAY (HZ / 5)
/*
* below this threshold, we consider thinktime immediate
@@ -1370,6 +1374,14 @@ cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
cfqg->vfraction = max_t(unsigned, vfr, 1);
}
+static inline u64 cfq_get_cfqg_vdisktime_delay(struct cfq_data *cfqd)
+{
+ if (!iops_mode(cfqd))
+ return CFQ_SLICE_MODE_GROUP_DELAY;
+ else
+ return CFQ_IOPS_MODE_GROUP_DELAY;
+}
+
static void
cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
{
@@ -1389,7 +1401,8 @@ cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
n = rb_last(&st->rb);
if (n) {
__cfqg = rb_entry_cfqg(n);
- cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
+ cfqg->vdisktime = __cfqg->vdisktime +
+ cfq_get_cfqg_vdisktime_delay(cfqd);
} else
cfqg->vdisktime = st->min_vdisktime;
cfq_group_service_tree_add(st, cfqg);