Re: LFS performance and kern.maxvnodes

On 9/10/07, Simon Burge <simonbnetbsd.org> wrote:

>On 512MB RAM machines I tend to use 128k as a
> minimum as well.

On my desktop system with 1GB RAM, 262144 seems to yield the
best
results for me (I've mainly used untarring pkgsrc as a test
thusfar).
At times going higher can help, but that's not that often
for me.
Thus, 128k seems like a reasonably conservative default--at
least for
machines with lots of memory.

Another thing I was going to propose was setting sysctl.conf
defaults
from sysinst using basic heuristics, taking into account [at
least]
the amount of system memory and anticipated workload.
We could then use this information to help suggest more
intelligent
defaults for things such as base filesystem layout and
bsize/fsize,
etc.

--Blair

On Mon, Sep 10, 2007 at 09:54:35PM -0400, Blair Sadewitz
wrote:
 > Another thing I was going to propose was setting
sysctl.conf defaults
 > from sysinst using basic heuristics, taking into
account [at least]
 > the amount of system memory and anticipated workload.
 > We could then use this information to help suggest
more intelligent
 > defaults for things such as base filesystem layout and
bsize/fsize,
 > etc.

I'm not going to say this is a bad idea - but in this case
wouldn't it
be better to make the kernel default smarter? Then you don't
have
wired-down values in /etc that go out of date when the
hardware gets
rearranged.

There's already code in init_main.c that checks the default
MAXUSERS-based value for being too low and substitutes
"1% of memory"
(based on the size of struct vnode), resulting in 62.4
vnodes per
megabyte. With the default MAXUSERS of 32 this kicks in when
you have
over 12 megabytes of RAM. It wouldn't be difficult to pump
this up
more for larger memory sizes.

-- 
   - David A. Holland / dhollandeecs.harvard.edu