Re: kern/55166: uvm_pdpolicy_clock params (anon/exec/file max/min)defaults

[SODA Noriyuki <soda-netbsd2020%yuruyuru.net@localhost>]

>>>>> On Mon, 13 Apr 2020 19:55:11 +0200,
	Joerg Sonnenberger <joerg%bec.de@localhost> said:

>> >  filemax seems questionable to me, the rest sound a useful default for
>> >  systems with <= 16MB RAM. 
>> 
>> I guess the default BUFCACHE (vm.bufcache / vm.bufmem, 15% of RAM) is
>> enough and no extra file cache is necessary for less memory systems.

> But the buffer cache is only used for meta-data, not for regular
> caching?

That's right.
But on machines which are under memory shortage, data cache is not
important, only meta-data is worth caching.

At that time when I was using a machine with insufficient memory
(it was 2004), I used to use the following setting:
	vm.anonmin=10
	vm.anonmax=80
	vm.execmin=0
	vm.execmax=2
	vm.filemin=0
	vm.filemax=1

I first tried the following setting:
	vm.anonmin=10
	vm.anonmax=80
	vm.execmin=10
	vm.execmax=50
	vm.filemin=5
	vm.filemax=30

then I decreased vm.filemax from 30 to 10.

then I decreased vm.file* as follows:
	vm.filemin:  5 -> 2
	vm.filemax: 10 -> 4

then I decreased vm.exec* as follows:
	vm.execmin: 10->0
	vm.execmax: 50->15
(this was the setting I posted to tech-kern on Aug 2004:
 https://muc.lists.netbsd.port.pmax.narkive.com/K45d5dZd/leaner-kernel-more-memory-for-user-apps#post2
 I cannot find this in mail-index.netbsd.org somehow)

then I decreased vm.file* as follows:
	vm.filemin:  2 -> 0
	vm.filemax:  4 -> 1

and then I decreased vm.exec* as follows:
	vm.execmax: 15-> 2
and this was the final setting I used to use at that age.

Note that the machine I used had 128MB RAM, that's far more
larger than m68k machines.

As mrg wrote in above mail archive, vm.filemax is not complete
upper limit.  The VM system gives more memory to file cache
if there is free memory.  So, vm.filemax=1 is not a problem at all.
-- 
soda