Re: [PATCH v3 1/6] rtmutex: Deboost before waking up the top waiter

2016-04-20 Thread Peter Zijlstra
On Wed, Apr 20, 2016 at 02:43:29PM +0200, Thomas Gleixner wrote: > > So its semantically icky to have the two tasks running off the same > > state and practically icky when you consider bandwidth inheritance -- > > where the boosted task wants to explicitly modify the state of the > > booster. > >

Re: [PATCH v3 1/6] rtmutex: Deboost before waking up the top waiter

2016-04-20 Thread Thomas Gleixner
On Wed, 20 Apr 2016, Peter Zijlstra wrote: > On Mon, Apr 18, 2016 at 11:02:28AM +0200, Thomas Gleixner wrote: > > On Mon, 18 Apr 2016, Xunlei Pang wrote: > > > We add a preempt_disable() before deboost to avoid the breakage, > > > there's also some comment about this in the patch's code. > > > > S

Re: [PATCH v3 1/6] rtmutex: Deboost before waking up the top waiter

2016-04-20 Thread Peter Zijlstra
On Mon, Apr 18, 2016 at 11:02:28AM +0200, Thomas Gleixner wrote: > On Mon, 18 Apr 2016, Xunlei Pang wrote: > > On 2016/04/18 at 16:23, Thomas Gleixner wrote: > > > On Thu, 14 Apr 2016, Xunlei Pang wrote: > > >> We should deboost before waking the high-prio task such that > > >> we don't run two tas

Re: [PATCH v3 1/6] rtmutex: Deboost before waking up the top waiter

2016-04-18 Thread Xunlei Pang
On 2016/04/18 at 17:02, Thomas Gleixner wrote: > On Mon, 18 Apr 2016, Xunlei Pang wrote: >> On 2016/04/18 at 16:23, Thomas Gleixner wrote: >>> On Thu, 14 Apr 2016, Xunlei Pang wrote: We should deboost before waking the high-prio task such that we don't run two tasks with the 'same' priori

Re: [PATCH v3 1/6] rtmutex: Deboost before waking up the top waiter

2016-04-18 Thread Thomas Gleixner
On Mon, 18 Apr 2016, Xunlei Pang wrote: > On 2016/04/18 at 16:23, Thomas Gleixner wrote: > > On Thu, 14 Apr 2016, Xunlei Pang wrote: > >> We should deboost before waking the high-prio task such that > >> we don't run two tasks with the 'same' priority. > > No. This is fundamentaly broken. > > > >

Re: [PATCH v3 1/6] rtmutex: Deboost before waking up the top waiter

2016-04-18 Thread Xunlei Pang
On 2016/04/18 at 16:23, Thomas Gleixner wrote: > On Thu, 14 Apr 2016, Xunlei Pang wrote: >> We should deboost before waking the high-prio task such that >> we don't run two tasks with the 'same' priority. > No. This is fundamentaly broken. > > T1 (prio 0) lock(X) > > --> preemption >

Re: [PATCH v3 1/6] rtmutex: Deboost before waking up the top waiter

2016-04-18 Thread Thomas Gleixner
On Thu, 14 Apr 2016, Xunlei Pang wrote: > We should deboost before waking the high-prio task such that > we don't run two tasks with the 'same' priority. No. This is fundamentaly broken. T1 (prio 0) lock(X) --> preemption T2 (prio 10)lock(X) boost(T1)