Re: [PATCH 08/35] autonuma: introduce kthread_bind_node()

Andrea Arcangeli
2012-05-29T18:16:16Z

On Tue, May 29, 2012 at 07:48:06PM +0200, Peter Zijlstra wrote:
> On Tue, 2012-05-29 at 19:44 +0200, Andrea Arcangeli wrote:
> >
> > But it'd be totally bad not to do the hard bindings to the cpu_s_ of
> > the node, and not using PF_THREAD_BOUND would just allow userland to
> > shoot itself in the foot. I mean if PF_THREAD_BOUND wouldn't exist
> > already I wouldn't add it, but considering somebody bothered to
> > implement it for the sake to make userland root user "safer", it'd be
> > really silly not to take advantage of that for knuma_migrated too
> > (even if it binds to more than 1 CPU).
>
> No, I'm absolutely ok with the user shooting himself in the foot. The
> thing exists because you can crash stuff if you get it wrong with
> per-cpu.
>
> Crashing is not good, worse performance is his own damn fault.

Some people don't like root to write to /dev/mem or rm -r /
either. I'm not in that camp, but if you're not in that camp, then you
should _never_ care to set PF_THREAD_BOUND, no matter if it's about
crashing or just slowing down the kernel.

If such a thing exists, well using it to avoid the user either to crash or
to screw with the system performance, can only be a bonus.