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Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!yarrina.connect.com.au!warrane.connect.com.au!godzilla.zeta.org.au!not-for-mail From: bde@zeta.org.au (Bruce Evans) Newsgroups: comp.os.386bsd.development Subject: Re: slow math library Date: 25 Nov 1994 21:24:01 +1100 Organization: Kralizec Dialup Unix Sydney - +61-2-837-1183, v.32bis v.42bis Lines: 39 Message-ID: <3b4e01$tua@godzilla.zeta.org.au> References: <EYMUB1UR@math.fu-berlin.de> <JTC.94Nov21103825@rtl.cygnus.com> NNTP-Posting-Host: localhost.zeta.org.au In article <JTC.94Nov21103825@rtl.cygnus.com>, J.T. Conklin <jtc@cygnus.com> wrote: >>>>>> "Thomas" == Thomas Graichen <graichen@omega.physik.fu-berlin.de> writes: > >Thomas> ... - i've also tried the msun lib (from 1.1.5) >Thomas> - but i can't see the big improvement - but floating point > ... >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. The main difference is probably that FreeBSD by default configures `msun' to not use the FPU or FPU emulator for math functions. Define HAVE_FPU if you have a real FPU (i387 or DX486 or pentium). >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 -D_IEEE_LIBM is the default for FreeBSD-1.1.5. `-D_MULTI_LIBM -D_POSIX_MODE -D_IEEE_LIBM' is the default for FreeBSD-2.0, but this combination of defines is bogus. It is actually almost equivalent to -D_IEEE_LIBM. -D_POSIX_MODE is the "correct" default. Unfortunately, it breaks IEEEish error reporting (NaNs get converted to numbers). >really think it can make that much of a difference, since it only >effects error handling. Yes, it should only slow down math functions by no more than a few percent. Bruce -- Bruce Evans bde@zeta.org.au