Messages in this thread | | | Date | Fri, 8 May 2020 11:09:25 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH updated v2] sched/fair: core wide cfs task priority comparison |
| |
On Fri, May 08, 2020 at 04:44:19PM +0800, Aaron Lu wrote: > On Wed, May 06, 2020 at 04:35:06PM +0200, Peter Zijlstra wrote:
> > Aside from this being way to complicated for what it does -- you > > could've saved the min_vruntime for each rq and compared them with > > subtraction -- it is also terminally broken afaict. > > > > Consider any infeasible weight scenario. Take for instance two tasks, > > each bound to their respective sibling, one with weight 1 and one with > > weight 2. Then the lower weight task will run ahead of the higher weight > > task without bound. > > I don't follow how this could happen. Even the lower weight task runs > first, after some time, the higher weight task will get its turn and > from then on, the higher weight task will get more chance to run(due to > its higher weight and thus, slower accumulation of vruntime).
That seems to assume they're mutually exclusive. In that case, as I argued, we only have a single runqueue and then yes it works. But if they're not exclusive, and can run concurrently, it comes apart.
| |