On Wed, 19 Mar 2014 15:43:39 -0400 Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > On Wed, 19 Mar 2014 20:34:07 +0100 > Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > > On Wed, Mar 19, 2014 at 03:12:52PM -0400, Steven Rostedt wrote: > > > My question to Tejun is, if we create another workqueue, to add the > > > rdata->work to, would that prevent the above problem? Or what other > > > fixes can we do? > > > > The way I understand workqueues is that we cannot guarantee concurrency > > like this. It tries, but there's no guarantee. > > > > WQ_MAX_ACTIVE seems to be a hard upper limit of concurrent workers. So > > given 511 other blocked works, the described problem will always happen. > > > > Creating another workqueue doesn't actually create more threads. > > But I noticed this: > > Before patch: > > # ps aux |grep cifs > root 3119 0.0 0.0 0 0 ? S< 14:17 0:00 [cifsiod] > > After patch: > > # ps aux |grep cifs > root 1109 0.0 0.0 0 0 ? S< 15:11 0:00 [cifsiod] > root 1111 0.0 0.0 0 0 ? S< 15:11 0:00 [cifsiord] > > It looks to me that it does create new threads. > Or is that just the rescuer thread? I can rewrite the patch to use kthread_work instead too. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
