At Fri, 24 Apr 2020 10:18:10 +0100, Sad Clouds <cryintothebluesky%gmail.com@localhost> wrote:
Subject: Re: Linux compat and swap
>
> But what is the value of vm.filemax? It tells the system what
> percentage of memory to steal from other uses, but this is counter
> productive, since by stealing from vm.anon and vm.exec it can result in
> swapping and extra disk I/O, which is what vm.filemax is trying to
> avoid in the first place, that is unnecessary disk I/O.
>
> I think the behaviour needs fixing, i.e. if vm.filemax is about to push
> pages to swap, then it should stop.
Well, you (i.e. the system administrator) are in charge of setting the
balance.
If your systems are experiencing paging because they are both bulging
with constantly scanned anon pages and trolling through the filesystem
like crazy then you can lower vm.filemax.
On the other hand if you've got filemax too low, and the anon pages are
actually sitting idle most of the time, then lowering anonmin and
raising filemax might improve filesystem performance dramatically.
On my edit/build/test server I have a couple of GB out on swap because
it's basically all idle memory -- there are very few page faults to read
from swap during even "-j 12" builds. After 132 days uptime, with
numerous system and pkgsrc builds, all while running some rather bloated
long-running emacs processes, these are the paging stats (from vmstat -s)
480372 pagein requests
180517 pageout requests
0 pages swapped in
1442574 pages swapped out
and just:
15 faults with no memory
28 faults had to wait on pages
all a tiny fraction of:
1271146431 total faults taken
--
Greg A. Woods <gwoods%acm.org@localhost>
Kelowna, BC +1 250 762-7675 RoboHack <woods%robohack.ca@localhost>
Planix, Inc. <woods%planix.com@localhost> Avoncote Farms <woods%avoncote.ca@localhost>
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