Subject: Re: Simple thought...
To: NetBSD-current Discussion List <email@example.com>
From: Frank Kardel <Frank.Kardel@Acrys.COM>
Date: 06/10/2002 15:46:55
"Greg A. Woods" <firstname.lastname@example.org> said:
> I.e. if you have tons of RAM (more than necessary for the active page
> sets of all your running processes) then make BUFCACHE (much) bigger:
> options BUFCACHE=25 # use up to 25% of RAM
> That way _all_ disk accesses can benefit, regardless of filesystem.
With UBC there is also another interesting parameter generating much
joy when increased:
sysctl -w kern.maxvnodes=64000 (for bigger machines arount 700MB RAM)
The data-pages now hang off the vnodes in UBC if i read the hints everywhere
right. Now the more vnodes you have the more data can be tacked onto them.
Increasing the buffer cache only helps meta data and takes memory away for
vnode data caching. Try to look at the "vmstat buf" statistics page and look
for vnode data pages. My machine (768MB) usually caches around 500-600MB
file system data. And more - lingering vnodes do not need to be filled
from the buffer cache. Effects are that kernel ld-runs are completely filled
from memory (just written .o files) and the bufcache is only used for
moving meta data. Set me right if i overlooked something here.