Re: page fault scalability patch V11 [0/7]: overview
From: Bill Davidsen
Date: Mon Nov 22 2004 - 14:41:23 EST
Linus Torvalds wrote:
On Sat, 20 Nov 2004, Nick Piggin wrote:
The per thread rss may wrap (maybe not 64-bit counters), but even so,
the summation over all threads should still end up being correct I
think.
Yes. As long as the total rss fits in an int, it doesn't matter if any of
them wrap. Addition is still associative in twos-complement arithmetic
even in the presense of overflows.
If you actually want to make it proper standard C, I guess you'd have to
make the thing unsigned, which gives you the mod-2**n guarantees even if
somebody were to ever make a non-twos-complement machine.
I think other stuff breaks as well, I think I saw you post some example
code using something like (a & -a) or similar within the last few
months. Fortunately neither 1's comp or BCD are likeliy to return in
hardware. Big-end vs. little-end is still an issue, though.
--
-bill davidsen (davidsen@xxxxxxx)
"The secret to procrastination is to put things off until the
last possible moment - but no longer" -me
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