*BSD News Article 38209


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From: jtc@cygnus.com (J.T. Conklin)
Subject: Re: slow math library
In-Reply-To: graichen@omega.physik.fu-berlin.de's message of Mon, 21 Nov 1994 12:49:13 GMT
Message-ID: <JTC.94Nov21103825@rtl.cygnus.com>
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References: <EYMUB1UR@math.fu-berlin.de>
Date: Mon, 21 Nov 1994 18:38:25 GMT
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>>>>> "Thomas" == Thomas Graichen <graichen@omega.physik.fu-berlin.de> writes:

Thomas> in the last day's i tried freebsd (1.1) ... but i've found one
Thomas> problem for me - the math-library (floating-point-operations)
Thomas> seem to be very slow (factor 2-4 slower like under linux on
Thomas> the same machine) - i've also tried the msun lib (from 1.1.5)
Thomas> - but i can't see the big improvement - but floating point
Thomas> speed is important for me because i do mostly numerical stuff
Thomas> on that machine - can anybody tell me if there is a faster
Thomas> math-lib for freebsd - or if not - can somebody who knows
Thomas> something about this try to improve the mathlib

I maintain the SunPro fdlibm derived math library for NetBSD and
DJGPP.  I understand that the FreeBSD folks have integrated a copy I
gave to Jordan into their OS as "msun".

I'm surprised that you have found it to be so much slower than the
Linux libm.  Before someone can start addressing the differences, it
would be useful to know what (math) operations your programs use.

One thing that you might try is to recompile the library with
-D_IEEE_LIBM and without -D_MULTI_LIBM and -D_POSIX_MODE.  I don't
really think it can make that much of a difference, since it only
effects error handling.

	--jtc