From: | "Alexander Staubo" <alex(at)purefiction(dot)net> |
---|---|
To: | "Ron Johnson" <ron(dot)l(dot)johnson(at)cox(dot)net> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: What O/S or hardware feature would be useful for databases? |
Date: | 2007-06-16 23:20:48 |
Message-ID: | 88daf38c0706161620m1c084a13i6b3919b7e4333f0d@mail.gmail.com |
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Lists: | pgsql-general |
On 6/17/07, Ron Johnson <ron(dot)l(dot)johnson(at)cox(dot)net> wrote:
> On 06/16/07 17:05, Alexander Staubo wrote:
> > On 6/16/07, Ron Johnson <ron(dot)l(dot)johnson(at)cox(dot)net> wrote:
> >> > Hardware acceleration for quickly counting the number of
> >> > set/unset/matching bits?
> >>
> >> x86 doesn't already do that?
> >
> > I don't think so. The fastest way, I believe, is to use precomputed
> > lookup tables. Same for finding the least/most significant set/unset
> > bit, and other operations useful for dealing with bit vectors.
>
> A couple of new AMD Barcelona opcodes might help do that:
>
> http://www.anandtech.com/showdoc.aspx?i=2939&p=6
Very cool. Thanks for the pointer.
Alexander.
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