Messages in this thread | | | Date | Tue, 18 Jun 2002 14:47:24 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: latest linus-2.5 BK broken |
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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.
>From a data structure standpoint, bitmaps are clearly the simplest dense 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
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