blkio: Recalculate the throttled bio dispatch time upon throttle limit change
o Currently any cgroup throttle limit changes are processed asynchronousy and
the change does not take affect till a new bio is dispatched from same group.
o It might happen that a user sets a redicuously low limit on throttling.
Say 1 bytes per second on reads. In such cases simple operations like mount
a disk can wait for a very long time.
o Once bio is throttled, there is no easy way to come out of that wait even if
user increases the read limit later.
o This patch fixes it. Now if a user changes the cgroup limits, we recalculate
the bio dispatch time according to new limits.
o Can't take queueu lock under blkcg_lock, hence after the change I wake
up the dispatch thread again which recalculates the time. So there are some
variables being synchronized across two threads without lock and I had to
make use of barriers. Hoping I have used barriers correctly. Any review of
memory barrier code especially will help.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index b06ca70..52c1213 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -124,7 +124,8 @@
if (blkiop->plid != blkg->plid)
continue;
if (blkiop->ops.blkio_update_group_weight_fn)
- blkiop->ops.blkio_update_group_weight_fn(blkg, weight);
+ blkiop->ops.blkio_update_group_weight_fn(blkg->key,
+ blkg, weight);
}
}
@@ -141,11 +142,13 @@
if (fileid == BLKIO_THROTL_read_bps_device
&& blkiop->ops.blkio_update_group_read_bps_fn)
- blkiop->ops.blkio_update_group_read_bps_fn(blkg, bps);
+ blkiop->ops.blkio_update_group_read_bps_fn(blkg->key,
+ blkg, bps);
if (fileid == BLKIO_THROTL_write_bps_device
&& blkiop->ops.blkio_update_group_write_bps_fn)
- blkiop->ops.blkio_update_group_write_bps_fn(blkg, bps);
+ blkiop->ops.blkio_update_group_write_bps_fn(blkg->key,
+ blkg, bps);
}
}
@@ -162,11 +165,13 @@
if (fileid == BLKIO_THROTL_read_iops_device
&& blkiop->ops.blkio_update_group_read_iops_fn)
- blkiop->ops.blkio_update_group_read_iops_fn(blkg, iops);
+ blkiop->ops.blkio_update_group_read_iops_fn(blkg->key,
+ blkg, iops);
if (fileid == BLKIO_THROTL_write_iops_device
&& blkiop->ops.blkio_update_group_write_iops_fn)
- blkiop->ops.blkio_update_group_write_iops_fn(blkg,iops);
+ blkiop->ops.blkio_update_group_write_iops_fn(blkg->key,
+ blkg,iops);
}
}