I have a single 32 bit processor OpenBSD 4.1 box and a single 64 bit processor FreeBSD 5.1 box that runs the exact same software on the 0x86.
When I type the following line at the shell prompt
The FreeBSD will slow down, but the OpenBSD doesn't. Any ideas why? Both boxes are running perl 5.8.8Code:perl -e 'while (--$ARGV[0] and fork) {}; while () {}' 4
Maybe OpenBSD has built in CPU quotas. It's meant to be a default secure OS.
I don't see any kind of cpu limits on either system.
Here is the ouput from OpenBSD
And here is the output from FreeBSD% ulimit -a
-t: cpu time (seconds) unlimited
-f: file size (blocks) unlimited
-d: data seg size (kbytes) 524288
-s: stack size (kbytes) 8192
-c: core file size (blocks) unlimited
-m: resident set size (kbytes) 465596
-l: locked-in-memory size (kb) 156810
-u: processes 24
-n: file descriptors 128
Code:% ulimit -a -t: cpu time (seconds) unlimited -f: file size (blocks) unlimited -d: data seg size (kbytes) 20000 -s: stack size (kbytes) 7000 -c: core file size (blocks) 0 -m: resident set size (kbytes) 15000 -l: locked-in-memory size (kb) 7000 -u: processes 20 -n: file descriptors 90 -N 9: socket buffer size (kb) unlimited -v: virtual memory size (kb) unlimited
Both systems only allow about 20 processes (24 and 20 respectively), so I expect your fork() calls are fairly limited.
As to the "grinding to a halt", I expect the difference in behaviour is determined (at least partly) by the way that the fork() call works - but perhaps also the priority given to "new processes" by the kernel. I've heard before that fork() loops "kill" machines because the OS gives new processes a higher priority.
The way fork works is that it either copies the entire process [this is "expensive"] or just copies the page-table such that the new pages are read-only, and then when a page is actually written to, it copies the page - this method is called "copy on write".
There may be many other reasons why there is a difference.
--
Mats
Compilers can produce warnings - make the compiler programmers happy: Use them!
Please don't PM me for help - and no, I don't do help over instant messengers.
