blkio: Wait on sync-noidle queue even if rq_noidle = 1
o rq_noidle() is supposed to tell cfq that do not expect a request after this
one, hence don't idle. But this does not seem to work very well. For example
for direct random readers, rq_noidle = 1 but there is next request coming
after this. Not idling, leads to a group not getting its share even if
group_isolation=1.
o The right solution for this issue is to scan the higher layers and set
right flag (WRITE_SYNC or WRITE_ODIRECT). For the time being, this single
line fix helps. This should not have any significant impact when we are
not using cgroups. I will later figure out IO paths in higher layer and
fix it.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 063dcbb..08b057b 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -3314,7 +3314,8 @@
* only if we processed at least one !rq_noidle request
*/
if (cfqd->serving_type == SYNC_WORKLOAD
- || cfqd->noidle_tree_requires_idle)
+ || cfqd->noidle_tree_requires_idle
+ || cfqq->cfqg->nr_cfqq == 1)
cfq_arm_slice_timer(cfqd);
}
}