* Bruce Evans <[EMAIL PROTECTED]> [010903 03:47] wrote:
> On Sun, 2 Sep 2001, Alfred Perlstein wrote:
>
> > The reason for the macro is that when the size paramter is a constant
> > there's an evil trick that makes selecting the malloc bucket really
> > cheap.
>
> That's not the reason. The size parameter is not constant since MALLOC()
> just calls malloc(). I wouldn't call the big conditional statement in
> BUCKETINDX() an evil trick. But perhaps it should be replaced by fls().
> A builtin fls() could handle constants just as well.
Well it was the original intent, in fact it was done such that
when a constant was used and the bucket wasn't empty the code
would expand to just a handful of instructions. This is
mentioned in "Design and Implementation".
As far as BUCKETINDX(), i almost thought that instead of doing
power of two buckets, we could use mod-32, this would do nifty
things like when we just barely go over 128 bytes for something
we don't waste nearly double our allocation.
--
-Alfred Perlstein [[EMAIL PROTECTED]]
'Instead of asking why a piece of software is using "1970s technology,"
start asking why software is ignoring 30 years of accumulated wisdom.'
'"Java" developer, like "special" Olympics, right?' - Bill Paul
To Unsubscribe: send mail to [EMAIL PROTECTED]
with "unsubscribe freebsd-current" in the body of the message
