Subject: Re: making swap *smaller* than memory can be painful
To: None <current-users@NetBSD.org>
From: None <roberto@redix.it>
List: current-users
Date: 02/02/2004 10:30:18
> roberto@redix.it wrote:
>> > On Fri, Jan 30, 2004 at 02:21:10PM +0100, roberto@redix.it wrote:
>> >> and, like this case where RAM > SWAP, what about do not using swap at
>> >> all (disabling swap, for example)?
>
>> > This should work too.
>
> It should but it depends on your carma. I've tried it with 256MB RAM. If
> you're using system as desktop machine or need even more memory than
> such machines, just forget it. It's not so funny when the kernel kills
> your X server.

I've a notebook with 512 MB RAM and 64MB swap on disk.
I'll to understand the UVM policies; for example if my RAM is being
exausted but there are many pages used for file buffers cache I'd like the
kernel will not kill any application but instead use the cache RAM.

> The rule (swap space == 2 * RAM) is of course very outdated.
> That was true when the OS reserved a page in swap for every physical page.
> Though, on a machine which serves dozens of users at the same time or
> needs a lot of virtual memory due to certain software, you'll usually need
> much more than 2*RAM swap space (or rather more RAM).
>
>> http://www.ccrc.wustl.edu/pub/chuck/tech/uvm/
>
> The presented information there is very old.

Do you know where to look for fresh informations ?

Thanks
Roberto