Still a complete system freeze when low on virtual memory..

[Elmar Krieger]

 >> If I run a memory intensive application and accidentally start a second 
instance
 >> in a different window, the computer freezes completely and needs a hard-reset
 >> with Fedora 3.
 >>
 >> In previous times, I could often at least kill the X-server and all 
applications
 >> with Ctrl+Alt+Backspace, or even better just close the console where I started
 >> the program. But no luck anymore nowadays..
 >>

 >What video card you use? If it is nvidia do you use their driver?
 >I had problems with it nvidia. Give more details about your hardware,
 >kernel and the application. Do you run it as root?

You are right, it's an nVIDIA Geforce4 with driver 66.29:
server glx vendor string: NVIDIA Corporation
OpenGL renderer string: GeForce4 Ti 4400/AGP/SSE2
OpenGL version string: 1.5.2 NVIDIA 66.29

Kernel is 2.6.9-1.667

The application is e.g. this trivial program, run as any user:
(I have 512MB physical memory and 5GB swap (as I am about to upgrade to 2 GB 
phys.mem)):

#include <stdlib.h>
#define MEMSIZE (300*1024*1024)

int main(int argc, char **argv)
{ char *mem;

   mem=malloc(MEMSIZE);
   while (1)
   { memset(mem,0,MEMSIZE); } }

If I run it twice in parallel, I freeze.

 > You also can slow down the system and make it respond many hours
 >later easy... use crtl-sysrq-<X> combination to remount ro, sync your
 >disks and reboot in such cases (enable in /etc/sysctl.conf).

Thanks a lot, that's the hint I was looking for. Great! (Just used it after 
running the test program above ;-)

Greetings,
Elmar

-- 
Elmar Krieger, PhD
YASARA Biosciences & CMBI Outstation Austria
Neue-Welt-Hoehe 13/b
A-8042 Graz
Austria/Europe

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