A Bulletin Board from the backside of the internet
http://bb.deadnet.se/
Print view

Addendum to "how" for OpenBSD
http://bb.deadnet.se/viewtopic.php?t=173		 Page 1 of 1
Author:  UndeTerminated [ Mon Apr 07, 2025 11:05 am ]
Post subject:  Addendum to "how" for OpenBSD
Section "how" of OCC explains that to limit RAM one should put "machine mem =512M" into boot.conf, but this does not seem to be respected what was pointed out by Solene and I checked that also on my own. Few things on this case:
(1) In /etc/login.conf user's class can have changed to datasize-max to 512M (or other value) - this seems to be partially respected, because modern web browser complains on not being able to eat enough memory, but it starts anyway and takes more than set limit,
(2) Other way would be to create big file with let's say /dev/zero or /dev/urandom and throw it into RAM, but this does not seem to work either,
(2.5) If you are stubborn enough, you can use this kernel patch to lock OS effectively on particular amount of RAM.
(3) Swap can be limited (if anyone wants that) by detaching swap partition and adding swap file using swapctl -d and swapctl -a. The easiest option is to put those commands into cron as root.

To run OpenBSD in single processor/thread mode put in /etc/boot.conf line boot /bsd.sp.

To slow down processor in OpenBSD, enable apmd and type apm -L, then hit Enter.

To sum up:
(1) If you really want to use OpenBSD for OCC, just buy 512M RAM stick duh. Or run it in vm.
(2) If not, use Linus uniX (use GRUB) or Plan9.
(3) The best reliable option is to get real, old hardware (also due to the fact that new CPUs are still faster in single thread than old CPUs).
Author:  oracle [ Mon Apr 07, 2025 3:02 pm ]
Post subject:  Re: Addendum to "how" for OpenBSD
Hm, this is troubling. I will investigate. Thank you.
Author:  tekk [ Mon Apr 07, 2025 4:39 pm ]
Post subject:  Re: Addendum to "how" for OpenBSD
UndeTerminated wrote: Mon Apr 07, 2025 11:05 am (3) The best reliable option is to get real, old hardware (also due to the fact that new CPUs are still faster in single thread than old CPUs).
This point is actually backwards if we're talking laptops. I ran into that issue in one of my experiments: my T480 would clock down to 400 mhz and stay there with apm -L and it'd feel much slower than a laptop 10 years its senior without apm -L.
Author:  UndeTerminated [ Mon Apr 07, 2025 5:03 pm ]
Post subject:  Re: Addendum to "how" for OpenBSD
tekk wrote: Mon Apr 07, 2025 4:39 pm
UndeTerminated wrote: Mon Apr 07, 2025 11:05 am (3) The best reliable option is to get real, old hardware (also due to the fact that new CPUs are still faster in single thread than old CPUs).
This point is actually backwards if we're talking laptops. I ran into that issue in one of my experiments: my T480 would clock down to 400 mhz and stay there with apm -L and it'd feel much slower than a laptop 10 years its senior without apm -L.
I put there big generalization, my experience with X230 is that with apm -L it winds down to "only" 800 MHz which is some slower than under apm -H. I do not have any real old (like before first Intel Core CPUs) laptop to make better comparison.
All times are UTC Page 1 of 1

Powered by phpBB® Forum Software © phpBB Limited