Re: [PATCH] proc-based cpu affinity user interface

From: Robert Love (rml@tech9.net)
Date: Tue Nov 27 2001 - 15:44:53 EST


On Tue, 2001-11-27 at 06:52, Ingo Molnar wrote:
> two comments. First, this has already been done - Andrew Morton has
> written such a patch.

I didn't know this until after I started, but it is irrelevant. Use
Andrew's if you want. However, I have incorporated some useful bits
from your patch and such that I think are superior.

> Second, as i've repeatedly said it, it's a failure to do this over /proc.
> What if /proc is not mounted? What if the process is in a chroot()
> environment, should it not be able to set its own affinity? This is a
> fundamental limitation of your approach, and *if* we want to export the
> cpus_allowed affinity to user-space (which is up to discussion), then the
> right way (TM) to do it is via a syscall.

OK OK OK ... we can argue all day over syscall vs. proc. Personally, I
don't find any of the arguments fruitful -- we make all sorts of
restrictions and "Don't do thats" in the kernel. Requiring procfs isn't
the end of the world.

When you posted your initial patch, I commented I liked it but was
interested in a proc variant. Some people were interested. Even you
said it wasn't a huge deal.

It doesn't matter to me, let's just expose _some_ interface to
userspace. Personally, I prefer procfs, but both implementations are
nicely done. I respect you too much to argue religion like this. I'll
push for either variant.

        Robert Love

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This archive was generated by hypermail 2b29 : Fri Nov 30 2001 - 21:00:28 EST