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From Brian Pane <bp...@pacbell.net>
Subject RE: [PATCH 2] example binary BUSEC patch for benchmarking only
Date Thu, 11 Jul 2002 15:41:58 GMT
On Thu, 2002-07-11 at 06:58, Bill Stoddard wrote:

> I ran a quick profile with this patch and it eliminated a couple of
> divisions (calls to __divi64 reduced from 4 to 2 in my test setup. your
> mileage may vary) which was good for 493 instructions. Still have 3 __divu64
> and 2 __divi64 calls. The three __divu64 calls are in the gettimeofday() CRT
> function, so there is not much we can do about these directly.  One __divi64
> is in apr_poll (convert microseconds to milliseconds. This can probably be
> optimized away). The other __divi64 is somewhere in cached_explode
> (util_time.c).

The only division that I know of in cached_explode() is:

    struct exploded_time_cache_element *cache_element =
        &(cache[seconds % TIME_CACHE_SIZE]);

Is that where the division operation is being generated
on your test system?

TIME_CACHE_SIZE is 16, specifically so that the compiler
can optimize away the division, but if there's still a
division being generated, we can replace it with
  "cache[seconds & TIME_CACHE_MASK]"

--Brian



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