Re: latest linus-2.5 BK broken

[Linus Torvalds]

On Tue, 18 Jun 2002, Cort Dougan wrote:
>
> I agree with you there.  It's not easy, and I'd claim it's not possible
> given that no-one has done it yet, to have a select() call that is speedy
> for both 0-10 and 1k file descriptors.

Actually, select() scales a lot better than poll() for _dense_ bitmaps.

The problem with non-scalability ends up being either sparse bitmaps
(minor problem, poll() can help) or just the work involved in watching a
large number of fd's (major problem, but totally unrelated to the bitmap
itself, and poll() usually makes it worse thanks to more data to be
moved).

Anyway, I was talking about the scalability of the _data_structure_, not 
the scalability performance-wise. Performance scalability is a non-issue 
for something like setaffinity(), since it's just not called at any rate 
approaching poll.

representation, and scale perfectly well to any reasonable number of 
CPU's.

If we end up using a default of 1024, maybe you'll have to recompile that
part of the system that has anything to do with CPU affinity in about
10-20 years by just upping the number a bit. Quite frankly, that's going
to be the _least_ of the issues.

		Linus