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Date: Wed, 16 Sep 2015 04:28:42 +0300
From: Solar Designer <solar@...nwall.com>
To: john-dev@...ts.openwall.com
Subject: Re: Judy array
On Wed, Sep 16, 2015 at 02:29:17AM +0300, Solar Designer wrote:
> real 0m57.785s
> user 4m21.243s
> sys 0m15.629s
>
> Oops. Almost same speed without actual prefetching. So maybe the
> re-arranged code is somehow faster in this case, even when I don't
> prefetch. Or maybe the CPU does speculative execution and thus
> prefetches anyway, using those pointers that the following few loop
> iterations would use (especially as the compiler unrolls the loop).
Implemented better prefetching, patch attached. New speed:
real 0m56.260s
user 4m9.024s
sys 0m16.240s
Best of several runs:
real 0m55.987s
user 4m7.024s
sys 0m16.082s
I think this should be committed, and I might get it into core tree
later. Even though we'll probably replace this with Fred's code soon.
I guess what I am doing is providing another baseline for comparison.
Alexander
View attachment "john-huge-prefetch.diff" of type "text/plain" (4518 bytes)
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