tree 4a07811529a16f9e25c4de44ef0bf2621d360249
parent 9026e521c0da0731eb31f9f9022dd00cc3cd8885
author Vivek Goyal <vgoyal@redhat.com> 1300827269 +0100
committer Jens Axboe <jaxboe@fusionio.com> 1300827300 +0100

blk-throttle: Reset group slice when limits are changed

Lina reported that if throttle limits are initially very high and then
dropped, then no new bio might be dispatched for a long time. And the
reason being that after dropping the limits we don't reset the existing
slice and do the rate calculation with new low rate and account the bios
dispatched at high rate. To fix it, reset the slice upon rate change.

https://lkml.org/lkml/2011/3/10/298

Another problem with very high limit is that we never queued the
bio on throtl service tree. That means we kept on extending the
group slice but never trimmed it. Fix that also by regulary
trimming the slice even if bio is not being queued up.

Reported-by: Lina Lu <lulina_nuaa@foxmail.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>