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authorCorrado Zoccolo <czoccolo@gmail.com>2009-11-26 10:02:58 +0100
committerJens Axboe <jens.axboe@oracle.com>2009-11-26 10:39:31 +0100
commit76280aff1c7e9ae761cac4b48591c43cd7d69159 (patch)
treef8b354746a96cf45a4d0fc980df4e37e3c37b173 /block
parente4a229196a7c676514c78f6783f8994f64bf681c (diff)
downloadlinux-stericsson-76280aff1c7e9ae761cac4b48591c43cd7d69159.tar.gz
cfq-iosched: idling on deep seeky sync queues
Seeky sync queues with large depth can gain unfairly big share of disk time, at the expense of other seeky queues. This patch ensures that idling will be enabled for queues with I/O depth at least 4, and small think time. The decision to enable idling is sticky, until an idle window times out without seeing a new request. The reasoning behind the decision is that, if an application is using large I/O depth, it is already optimized to make full utilization of the hardware, and therefore we reserve a slice of exclusive use for it. Reported-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Corrado Zoccolo <czoccolo@gmail.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block')
-rw-r--r--block/cfq-iosched.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 2c1086acddfa..15f7238f527f 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -260,6 +260,7 @@ enum cfqq_state_flags {
CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
CFQ_CFQQ_FLAG_sync, /* synchronous queue */
CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
+ CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
};
#define CFQ_CFQQ_FNS(name) \
@@ -286,6 +287,7 @@ CFQ_CFQQ_FNS(prio_changed);
CFQ_CFQQ_FNS(slice_new);
CFQ_CFQQ_FNS(sync);
CFQ_CFQQ_FNS(coop);
+CFQ_CFQQ_FNS(deep);
#undef CFQ_CFQQ_FNS
#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
@@ -2350,8 +2352,12 @@ cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
+ if (cfqq->queued[0] + cfqq->queued[1] >= 4)
+ cfq_mark_cfqq_deep(cfqq);
+
if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
- (sample_valid(cfqq->seek_samples) && CFQQ_SEEKY(cfqq)))
+ (!cfq_cfqq_deep(cfqq) && sample_valid(cfqq->seek_samples)
+ && CFQQ_SEEKY(cfqq)))
enable_idle = 0;
else if (sample_valid(cic->ttime_samples)) {
if (cic->ttime_mean > cfqd->cfq_slice_idle)
@@ -2849,6 +2855,11 @@ static void cfq_idle_slice_timer(unsigned long data)
*/
if (!RB_EMPTY_ROOT(&cfqq->sort_list))
goto out_kick;
+
+ /*
+ * Queue depth flag is reset only when the idle didn't succeed
+ */
+ cfq_clear_cfqq_deep(cfqq);
}
expire:
cfq_slice_expired(cfqd, timed_out);