Does FreeBSD kernel P-III re-compile also rebuild c-compiler

Does FreeBSD kernel P-III re-compile also rebuild c-compiler

Post by Anonymous Cowa » Wed, 11 Jul 2001 23:33:04



I'd like to increase performance by re-building my FreeBSD kernel with
the Pentium option. Will this also rebuild the c-compiler to generate
Pentium code? Will I have problems with FreeBSD pre-built packages?
--
tia
 
 
 

Does FreeBSD kernel P-III re-compile also rebuild c-compiler

Post by Michel TALO » Thu, 12 Jul 2001 00:25:56


: I'd like to increase performance by re-building my FreeBSD kernel with
: the Pentium option.

You have to indicate the correct type of the CPU in the Kernel config file.
This should make some very slight performance improvments.

: Will this also rebuild the c-compiler to generate
: Pentium code? Will I have problems with FreeBSD pre-built packages?

This will not rebuild the c-compiler and other userland. But you can do it.
At the end of the day you will gain nothing, because the optimisations in gcc
are not very efficient.

: --
: tia

--

Michel TALON

 
 
 

Does FreeBSD kernel P-III re-compile also rebuild c-compiler

Post by Rasput » Thu, 12 Jul 2001 00:38:58


In the last exciting episode of comp.unix.bsd.freebsd.misc,



>: I'd like to increase performance by re-building my FreeBSD kernel with
>: the Pentium option.

> You have to indicate the correct type of the CPU in the Kernel config file.
> This should make some very slight performance improvments.

>: Will this also rebuild the c-compiler to generate
>: Pentium code? Will I have problems with FreeBSD pre-built packages?

> This will not rebuild the c-compiler and other userland. But you can do it.
> At the end of the day you will gain nothing, because the optimisations in gcc
> are not very efficient.

Have a look at the CPUTYPE variable in /etc/defaults/make.conf, and copy
the relevant line into /etc/make.conf

(be warned this has been known to bite. YMMV.)
--
Boren's Laws:
        (1) When in charge, ponder.
        (2) When in trouble, delegate.
        (3) When in doubt, mumble.
Rasputin :: Jack of All Trades - Master of Nuns ::

 
 
 

Does FreeBSD kernel P-III re-compile also rebuild c-compiler

Post by pe.. » Thu, 12 Jul 2001 04:01:57



> I'd like to increase performance by re-building my FreeBSD kernel with
> the Pentium option. Will this also rebuild the c-compiler to generate
> Pentium code? Will I have problems with FreeBSD pre-built packages?

You probably will get no performance enhancements by creating a custom kernel
optimized for a specific processor, the reason is that the kernel usually
uses only a fraction of all time spent.

It's the applications that should consume your cpu. If you find
your system working with much "system time" you might have a badly
written application that needs recoding.

Quote:> --
> tia

--
Peter H?kanson        
        IPSec  Sverige      (At the Riverside of Gothenburg, home of Volvo)
           Sorry about my e-mail address, but i'm trying to keep spam out.
           Remove "icke-reklam"and "invalid"  and it works.
 
 
 

1. AIX PS/2 C-compiler bug (or is it me?)?

Hi -

I have AIX PS/2 (the latest and greatest: updates of C compiler and
base operating system as of 2/12/90), but I am unable to compile the
following simple program:

main()
{
        double d;
        long l;
        short s;
        int i;

        char *c;

        c = (char *) l;
        c = (char *) s;
        c = (char *) i;
        c = (char *) d;

...I get the following compile-time diagnostic:

        14.     c = (char *) s;
        15.     c = (char *) d; <<<<<
****** Error number 137 in line 14 of file test.c *****
****** Illegal type conversion *****
1 errors.  0 warnings.  16 lines.  File test.c

...BTW, this program compiles fine on AIX 2.2.1 on the RT (6150/125).

This code is an isolation of code in a much larger program.  The exact
same error occurs there, too (on the PS/2; RT is okay and the program
WORKS).

Any ideas?  Thanks.......

Pete Gregory          | uucp:   uunet!bally!pete            ________

Bally Systems, Inc.   | phone:  702-323-6156 x882         /   /||  \ \
255 Bell St.          | FAX:    702-323-5997             | |\/ ||  _  |
Reno, NV 89503        |                                  | |   ||   | |
                                                          \    ||__/ /
                                                           \________/   '71 MGB

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