Date: Tue, 24 Jun 2003 15:11:37 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: Tim Kientzle <kientzle@acm.org> Cc: hackers@freebsd.org Subject: Re: Page Coloring Defines in vm_page.h Message-ID: <200306242211.h5OMBb12095342@apollo.backplane.com> References: <20030624111942.GO31354@spc.org> <3EF8900A.6030803@acm.org>
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:Matthew Dillon wrote:
:> For example, prime number 3 an array size 8 will scan the array in
:> the following order N = (N + PRIME) & (ARRAY_SIZE_MASK).
:> N = (N + 3) & 7:
:>
:> 0 3 6 1 4 7 2 5 ... 0
:>
:> As you can see, all the array entries are covered before the sequence
:> repeats. .... Only certain prime number / power-of-2-array size
:> combinations have this effect, ....
:
:Ummmm.... Actually, Matt, the property you've stated is much more
:common than you seem to believe. If you generate a sequence
: N = ( N + Stride ) % ArraySize
:then you will visit every element of (0 ... ArraySize-1) as long as
I was just answering a question. Most people aren't interested in that
level of detail (or, if they are, I'm sure Terry would happily chime in),
they just want to know the purpose.
-Matt
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