On Tue, Sep 23, 2014 at 02:08:12AM -0400, Tejun Heo wrote: > From 83b06f4fc6ca2f7f3d706a168b71c248bdada668 Mon Sep 17 00:00:00 2001 > From: Tejun Heo <tj@xxxxxxxxxx> > Date: Tue, 23 Sep 2014 01:58:34 -0400 > > blk-mq uses percpu_ref for its usage counter which tracks the number > of in-flight commands and used to synchronously drain the queue on > freeze. percpu_ref shutdown takes measureable wallclock time as it > involves a sched RCU grace period. This means that draining a blk-mq > takes measureable wallclock time. One would think that this shouldn't > matter as queue shutdown should be a rare event which takes place > asynchronously w.r.t. userland. Applied to percpu/for-3.18 on top of the klude, its revert and the required percpu_ref changes. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
