Re: [RFC patch 1/2] sched: dynamically adapt granularity with nr_running

Peter Zijlstra
2010-09-13T13:54:52Z

On Mon, 2010-09-13 at 09:52 -0400, Steven Rostedt wrote:
> On Mon, 2010-09-13 at 10:41 +0200, Peter Zijlstra wrote:
>
> > Yeah, without it you can starve the already running task on massive
> > forks.
> >
> > Still, I'm not quite sure why people really care about fork() on time
> > sensitive paths, its a very expensive thing to do, pre-fork() and wake
> > when you need it, is what I would say.
>
> Fork is used all over the place in Linux. Every shell script uses it to
> execute commands. Bad fork behavior shows up in just doing a build of
> the kernel.

Sure, but there's a difference between bad fork behaviour and the lowest
possible latency. But maybe I'm too paranoid from doing -rt, but the
first thing I'd do is get all resource allocations out from your fast
path.