Re: [BENCHMARK] 2.5.47{-mm1} with contest

From: Bill Davidsen (davidsen@tmr.com)
Date: Thu Nov 21 2002 - 13:25:09 EST


On Thu, 21 Nov 2002, Andrew Morton wrote:

> Dave Jones wrote:

> We'd buy a bit by arranging for the in-kernel copy of the fp state
> to have the same layout as the hardware. That way it can be done in
> a single big, fast, well-aligned slurp. But for some reason that code has
> to convert into and out of a different representation.
>
> But the real low-hanging fruit here is the observation that the
> test application doesn't use floating point!!!
>
> Maybe we need to take an fp trap now and then to "poll" the application
> to see if it is still using float.

I thought we used to do that and someone (Linus??) thought the complexity
didn't justify the saving. Always seemed like a good idea to me, but with
the various types of processor we have today, it's harder to say what wins
until benchmarks are done.

Hopefully someone has a better memory than I about this.

-- 
bill davidsen <davidsen@tmr.com>
  CTO, TMR Associates, Inc
Doing interesting things with little computers since 1979.

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