On Tue, Nov 08, 2016 at 08:29:49PM +0100, Daniel Bristot de Oliveira wrote: > > > On 11/08/2016 07:05 PM, Peter Zijlstra wrote: > >> > > >> > I know what we want to do, but there's some momentous problems that > >> > need to be solved first. > > Like what? > > The problem is that using RT_RUNTIME_SHARE a CPU will almost always > borrow enough runtime to make a CPU intensive rt task to run forever... > well not forever, but until the system crash because a kworker starved > in this CPU. Kworkers are sched fair by design and users do not always > have a way to avoid them in an isolated CPU, for example. > > The user then can disable RT_RUNTIME_SHARE, but then the user will have > the CPU going idle for (period - runtime) at each period... throwing CPU > time in the trash. So why is this a problem? You really should not be running that much FIFO tasks to begin with. So I'm willing to take out (or at least default disable RT_RUNTIME_SHARE). But other than this, this never really worked to begin with. So it cannot be a regression. And we've lived this long with the 'problem'. And that means this is a 'feature' and that means I say no. We really should be doing the right thing here, not make a bigger mess. -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
