/hg/release/icedtea6-1.10: JamVM: Base default min and max heap ...

[Xerxes Rånby]

Hi the IcedTea buildbot found a multiplication overflow bug in the new
default min max heap size on physical memory calculation code when running JamVM on a system with a lot of RAM.

http://git.berlios.de/cgi-bin/cgit.cgi/jamvm/commit/?id=cc6997003dd65ba5a32df471b7c0547fba9769f2
http://builder.classpath.org/icedtea/buildbot/builders/icedtea6-jaunty-ia32-quick-jamvm/builds/35

Testcase:
$ cat test.c
#include <stdio.h>
#include <unistd.h>

long getPhysicalMemory() {
 long num_pages = sysconf(_SC_PHYS_PAGES);
 printf("num_pages=%ld\n",num_pages);
 long page_size = sysconf(_SC_PAGESIZE);
 printf("page_size=%ld\n",page_size);
 return num_pages * page_size;
}

int main(void) {
  printf("getPhysicalMemory=%ld\n",getPhysicalMemory());
  return 0;
}

Output:
JamVM fails to launch on the icedtea buildbot with 3.6G of RAM
$gcc test.c
$ ./a.out
num_pages=901305
page_size=4096
getPhysicalMemory=-603222016
$ free
             total       used       free     shared    buffers     cached
Mem:       3605220    3335356     269864          0     178496    2461148
-/+ buffers/cache:     695712    2909508
Swap:      6072528     163624    5908904
$ /home/buildbot/icedtea/icedtea6-jaunty-ia32-quick-jamvm/build/openjdk.build/j2sdk-image/bin/java -version
Couldn't allocate the heap; try reducing the max heap size (-Xmx)
: Cannot allocate memory
$ /home/buildbot/icedtea/icedtea6-jaunty-ia32-quick-jamvm/build/openjdk.build/j2sdk-image/bin/java -Xmx2700m -version
java version "1.6.0_22"
IcedTea6 Runtime Environment (1.11pre+rf2b14c2da1ee) (Ubuntu build 1.6.0_22-b22)
JamVM (build 1.6.0-devel, inline-threaded interpreter with stack-caching)



JamVM work on my test machine with 2Gb of RAM
$gcc test.c
$ ./a.out
num_pages=494269
page_size=4096
getPhysicalMemory=2024525824
$ free
             total       used       free     shared    buffers     cached
Mem:       1977076    1919960      57116          0      35340     932724
-/+ buffers/cache:     951896    1025180
Swap:      3478036     106324    3371712
$ ./icedtea6-1.10-jamvm/openjdk.build/j2sdk-image/bin/java -version
java version "1.6.0_22"
IcedTea6 Runtime Environment (1.10.1pre+r18a72e54ee0e+) (Ubuntu build 1.6.0_22-b22)
JamVM (build 1.6.0-devel, inline-threaded interpreter with stack-caching)


> changeset 1e6b2d4fbb71 in /hg/release/icedtea6-1.10
> details: http://icedtea.classpath.org/hg/release/icedtea6-1.10?cmd=changeset;node=1e6b2d4fbb71
> author: Xerxes R?nby <xerxes at zafena.se>
> date: Thu Mar 24 13:06:27 2011 +0100
>
> 	JamVM: Base default min and max heap size on physical memory.
>
> 	2011-03-24 Xerxes Ranby <xerxes at zafena.se>
>
> 	 JamVM: Base default min and max heap size on physical
> 	memory.
> 		* NEWS: Updated.
> 		* Makefile.am (JAMVM_VERSION): Updated to latest JamVM
> 	revision. (JAMVM_SHA256SUM): Updated.
>