Subject: Re: Finally increasing vm.execmin by default
To: Todd Vierling <firstname.lastname@example.org>
From: Gavan Fantom <email@example.com>
Date: 10/28/2005 20:11:47
Todd Vierling wrote:
> Will someone please tell me what kind of box will need 1.6 MiB or less of
> persistent text pages when fully running, if the box is doing anything in
> userspace applications? Something is really wrong here with the defaults.
> I would suggest a compromise of something along the lines of:
> vm.anonmax=70 # default = 80
> vm.anonmin=10 # default
> vm.execmax=40 # default = 30
> vm.execmin=20 # default = 5
> vm.filemax=40 # default = 50
> vm.filemin=10 # default
> Of all these, however, vm.execmin is the most critical (hence the subject
> line). The default should be nowhere below 20, and currently it's only one
> fourth of that. Forget the low memory boxes for a moment -- we're
> sacrificing systems with typically modest memory just to make heavily
> decked-out systems run a couple percent faster. No wonder NetBSD is
> publicly perceived as having serious VM paging problems.
> If a system has many GiB of memory, it should be up to the admin to lower
> the execmin in order to gain yet more fs or anon page cache. It should
> *not* be up to the users of systems with modest memory to raise them.
This says to me that the variables themselves could do with a rethink,
not just the default values. Perhaps there's something other than a
percentage that makes for a better constant default?
How does the ideal size of execmin (and, perhaps the other mins) vary
with total system memory size?
Gillette - the best a man can forget