Re: [tip:sched/core] sched: Turn off child_runs_first

[Pavel Machek]

Hi!

> > > It hurts 'optimal' make -j<NR_CPUS> workloads as make jobs
> > > get preempted by child tasks, reducing parallelism.
> > 
> > Wasn't one of the reasons why we historically did child_runs_first 
> > was so that for fork/exit workloads, the child has a chance to 
> > exec the new process?  If the parent runs first, then more pages 
> > will probably need to be COW'ed.
> 
> That kind of workload should be using vfork() anyway, and be even 
> faster because it can avoid the fork overhead, right?

Well.. one should not have to update userspace to keep
performance.... and vfork is extremely ugly interface.

-- 
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