Date: Sat, 11 Nov 2000 17:43:56 -0500 (EST) From: Mitch Collinsworth <mitch@ccmr.cornell.edu> To: Michael Joyner <wolfieee@wolf.dyns.cx> Cc: freebsd-questions@freebsd.org Subject: Re: Linux malloc better on FreeBSD than FreeBSD malloc? Message-ID: <Pine.LNX.4.10.10011111741520.16421-100000@dragon.ccmr.cornell.edu> In-Reply-To: <3A0DC4FB.1DAFF251@wolf.dyns.cx>
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I'll check those out, but just to be clear, are you suggesting these
could explain why the Linux binary running on FreeBSD was able to do
what the FreeBSD binary could not?
-Mitch
On Sat, 11 Nov 2000, Michael Joyner wrote:
> a shot in the dark...
> think this comment from LINT might help?
> #
> # Certain applications can grow to be larger than the 128M limit
> # that FreeBSD initially imposes. Below are some options to
> # allow that limit to grow to 256MB, and can be increased further
> # with changing the parameters. MAXDSIZ is the maximum that the
> # limit can be set to, and the DFLDSIZ is the default value for
> # the limit. You might want to set the default lower than the
> # max, and explicitly set the maximum with a shell command for processes
> # that regularly exceed the limit like INND.
> #
> options MAXDSIZ="(256*1024*1024)"
> options DFLDSIZ="(256*1024*1024)"
>
>
> Mitch Collinsworth wrote:
> >
> > Well I hope that subject was provocative enough to generate some
> > interest! :-) Here's a strange situation that's bugging me. I
> > recently changed jobs, into a dept that's heavily Linux-based. I
> > of course have different preferences, but need to demonstrate
> > technical superiority if any changes are going to happen. An
> > opportunity just arose to make some comparisons between Linux and
> > FreeBSD in maximum process size. We have some new systems with
> > 4 GB RAM each that will be made available for running large batch
> > jobs.
> >
> > We have a very simple test program that malloc's successively larger
> > and larger blocks of memory until it fails, freeing the current blocks
> > after each successful trial. The strange thing is that the test
> > program runs much farther on FreeBSD using the Linux binary in
> > compatibility mode than it does using the binary compiled on FreeBSD!
> > Included below are the output from each binary and the source. Can
> > anyone explain these results?
> >
> > A second question, which is the primary issue we were trying to
> > discover is if it is possible for a single process to malloc more than
> > 2 GB of memory. FreeBSD supposedly supports up to 4 GB (on Intel
> > hardware), but does anyone know if there is still a 2 GB per process
> > limit? And if a single process can be larger than 2 GB, is there a
> > 2 GB limit on any single malloc with that process?
> >
> > For comparison purposes, the Linux answers to these questions are that
> > with a special "bigmem" patch installed, a process can be larger than
> > 2 GB, but any single malloc is still limited to 2 GB.
> >
> > The system the tests are being run on is a 900 MHz Xeon running
> > FreeBSD 4.1-R with 1 GB RAM and 18 GB swap:
> >
> > ruby> swapinfo -k
> > Device 1K-blocks Used Avail Capacity Type
> > /dev/da0s3b 511872 0 511872 0% Interleaved
> > /dev/rda1c 17783108 0 17783108 0% Interleaved
> > Total 18294980 0 18294980 0%
> >
> > ------FreeBSD results---------
> > # with FreeBSD compiled binary
> > ruby> ./grab-fbsd
> > Allocated f 268435455
> > Punt g at 268435455
> >
> > # with Linux compiled binary run in compatibility mode
> > ruby> ./grab-linux
> > Allocated f 268435455
> > Allocated g 268435455
> > Allocated f 536870911
> > Allocated g 536870911
> > Allocated f 805306367
> > Allocated g 805306367
> > Allocated f 1073741823
> > Allocated g 1073741823
> > Allocated f 1342177279
> > Punt g at 1342177279
> >
> > ------source-----------------
> > #include <stdio.h>
> > #include <stdlib.h>
> > #include <unistd.h>
> >
> > int
> > main(int argc, char *argv[]){
> >
> > unsigned long i, s2;
> > char *foo, *goo;
> >
> > for (i=1; i<100; i++){
> > foo = (char *) malloc(s2=(unsigned long)i*(1024*1024*256)-1);
> > if ( foo == NULL) {
> > printf("Punt f at %lu\n", s2);
> > exit(1);
> > } else {
> > printf("Allocated f %lu\n",s2);
> > }
> > goo = (char *) malloc(s2=(unsigned long)i*(1024*1024*256)-1);
> > if ( goo == NULL) {
> > printf("Punt g at %lu\n", s2);
> > exit(1);
> > } else {
> > printf("Allocated g %lu\n",s2);
> > }
> > sleep(4);
> > free(foo);
> > free(goo);
> > }
> > }
> > -----------------------------
> >
> > Thanks for any help. Please cc: me on replies. I'm no longer getting
> > -questions directly.
> >
> > -Mitch
> >
> > To Unsubscribe: send mail to majordomo@FreeBSD.org
> > with "unsubscribe freebsd-questions" in the body of the message
>
> --
>
> ===
> Unix is like a wigwam -- no Gates, no Windows, and an Apache inside.
> ===
> ---
> Michael Joyner
> Systems Administrator
> mjoyner@rv1.dynip.com
>
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