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authorShaohua Li <shaohua.li@intel.com>2011-07-12 14:24:55 +0200
committerJens Axboe <jaxboe@fusionio.com>2011-07-12 14:24:55 +0200
commitf5f2b6ceb23e02ff35c6dbc6a39aa776ace99cda (patch)
tree19ea26a1832c03c1c221675d3372b86abd12cc83 /block
parent383cd7213f95a2784ab5038fe292844178768b82 (diff)
downloadvexpress-lsk-f5f2b6ceb23e02ff35c6dbc6a39aa776ace99cda.tar.gz
CFQ: add think time check for service tree
Currently when the last queue of a service tree has no request, we don't expire the queue to hope request from the service tree comes soon, so the service tree doesn't miss its share. But if the think time is big, the assumption isn't correct and we just waste bandwidth. In such case, we don't do idle. [global] runtime=10 direct=1 [test1] rw=randread ioengine=libaio size=500m directory=/mnt filename=file1 thinktime=9000 [test2] rw=read ioengine=libaio size=1G directory=/mnt filename=file2 patched base test1 41k/s 33k/s test2 15868k/s 15789k/s total 15902k/s 15817k/s A slightly better To check if the patch changes behavior of queue without think time. I also tried to give test1 2ms think time or no think time. The test has variation even without the patch, but the average throughput doesn't change with/without the patch. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'block')
-rw-r--r--block/cfq-iosched.c34
1 files changed, 30 insertions, 4 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 56255599a02..baa90606f01 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -87,9 +87,10 @@ struct cfq_rb_root {
unsigned count;
unsigned total_weight;
u64 min_vdisktime;
+ struct cfq_ttime ttime;
};
-#define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, .left = NULL, \
- .count = 0, .min_vdisktime = 0, }
+#define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \
+ .ttime = {.last_end_request = jiffies,},}
/*
* Per process-grouping structure
@@ -391,6 +392,18 @@ CFQ_CFQQ_FNS(wait_busy);
j++, st = i < IDLE_WORKLOAD ? \
&cfqg->service_trees[i][j]: NULL) \
+static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
+ struct cfq_ttime *ttime, bool group_idle)
+{
+ unsigned long slice;
+ if (!sample_valid(ttime->ttime_samples))
+ return false;
+ if (group_idle)
+ slice = cfqd->cfq_group_idle;
+ else
+ slice = cfqd->cfq_slice_idle;
+ return ttime->ttime_mean > slice;
+}
static inline bool iops_mode(struct cfq_data *cfqd)
{
@@ -1955,7 +1968,8 @@ static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
* Otherwise, we do only if they are the last ones
* in their service tree.
*/
- if (service_tree->count == 1 && cfq_cfqq_sync(cfqq))
+ if (service_tree->count == 1 && cfq_cfqq_sync(cfqq) &&
+ !cfq_io_thinktime_big(cfqd, &service_tree->ttime, false))
return true;
cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
service_tree->count);
@@ -3220,8 +3234,11 @@ static void
cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
struct cfq_io_context *cic)
{
- if (cfq_cfqq_sync(cfqq))
+ if (cfq_cfqq_sync(cfqq)) {
__cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
+ __cfq_update_io_thinktime(&cfqq->service_tree->ttime,
+ cfqd->cfq_slice_idle);
+ }
}
static void
@@ -3550,7 +3567,16 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq)
cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
if (sync) {
+ struct cfq_rb_root *service_tree;
+
RQ_CIC(rq)->ttime.last_end_request = now;
+
+ if (cfq_cfqq_on_rr(cfqq))
+ service_tree = cfqq->service_tree;
+ else
+ service_tree = service_tree_for(cfqq->cfqg,
+ cfqq_prio(cfqq), cfqq_type(cfqq));
+ service_tree->ttime.last_end_request = now;
if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
cfqd->last_delayed_sync = now;
}