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' priority. >>> No. This is fundamentaly broken. >>> >>> T1 (prio 0) lock(X) >>> >>> --> preemption >>> >>> T2 (prio 10) lock(X) >>> boost(T1) >>> schedule() >>> >>> T1 (prio 10) unlock(X) >> We add a preempt_disable() before deboost to avoid the breakage, >> there's also some comment about this in the patch's code. > So the changelog is useless and misleading. Neither does it explain what's > wrong with having two tasks with the same priority in running state.
Sorry about that, will improve it. Regards, Xunlei > > Thanks, > > tglx > > > >
