Subject: Re: making swap *smaller* than memory can be painful
To: Manuel Bouyer <email@example.com>
From: None <firstname.lastname@example.org>
Date: 01/30/2004 14:21:10
> On Thu, Jan 29, 2004 at 05:21:58PM +0100, email@example.com wrote:
>> > On Tue, Jan 27, 2004 at 11:00:06AM +1000, George Michaelson wrote:
>> >> I decided the "2x memory for swap" rule probably didn't apply any
>> >> and made my system have 128mb swap for 256mb memory. Until today,
>> >> is.
>> >> last night, moving a 1.5Gb ghost image in via ssh, with some local
>> >> folder
>> >> activity in email and a browser, I had ls processes crap out with:
>> >> Jan 26 18:50:00 dhcppc1 /netbsd: UVM: pid 1424 (ls), uid 101 killed:
>> >> out of swap
>> >> indeed top showed that the Swap utilization was extreme.
>> > What did it report for memory ? especially the Exec, File and Free
>> > ?
>> > You may need to adjust some uvm parameters for your workload ...
>> Like George, on my notebook I've configured swap at about 1/2 of actual
>> RAM (only for space saving):
>> total RAM= 512 MB
>> swap 256 MB (instead of 1GB)
>> Please, could you explain to me the meanings of the memory fields you
>> mention? how to interpret them?
> "Exec" is the memory used by executable pages, "File" the memory used for
> buffer cache. Both can be reclaimed for other usage, so if a process gets
> killed because the system is "out of swap" while a lot of memory is
> to one of these types, there's something which needs to be tuned, or
> broken in the VM system.
and, like this case where RAM > SWAP, what about do not using swap at all
(disabling swap, for example)?
could you suggest to me any link or doc on the UVM tuning topic?