Re: [PATCH] blk-throttle: fix zero wait time for iops throttled group

2019-07-09 Thread Konstantin Khlebnikov
On 08.07.2019 22:08, Liu Bo wrote: On Mon, Jul 08, 2019 at 06:29:57PM +0300, Konstantin Khlebnikov wrote: After commit 991f61fe7e1d ("Blk-throttle: reduce tail io latency when iops limit is enforced") wait time could be zero even if group is throttled and cannot issue requests right now. As a

Re: [PATCH] blk-throttle: fix zero wait time for iops throttled group

2019-07-08 Thread Liu Bo
On Mon, Jul 08, 2019 at 06:29:57PM +0300, Konstantin Khlebnikov wrote: > After commit 991f61fe7e1d ("Blk-throttle: reduce tail io latency when iops > limit is enforced") wait time could be zero even if group is throttled and > cannot issue requests right now. As a result throtl_select_dispatch()

[PATCH] blk-throttle: fix zero wait time for iops throttled group

2019-07-08 Thread Konstantin Khlebnikov
After commit 991f61fe7e1d ("Blk-throttle: reduce tail io latency when iops limit is enforced") wait time could be zero even if group is throttled and cannot issue requests right now. As a result throtl_select_dispatch() turns into busy-loop under irq-safe queue spinlock. Fix is simple: always