mbuf patch with sysctl suggestions too

[Bruce Evans]

On Wed, 24 Jan 2007, Randall Stewart wrote:

> Bruce Evans wrote:
>> It has a lot of style bugs (4 per line on so,me lines) (mainly weird
>> whitespace starting with tab lossage).
>> 
> That has to do with me using emacs I think.. I will be running that
> section of code through the style9 (s9indent) stuff that George
> gave me...  so that should take care of the space <-> tab issues
> and other stuff...

I wouldn't trust an editor to get this right.  indent(1) gets closer,
but still gets so much wrong that every change that it wants to make
must be reviewed manually.

> I think Pyun is right though.. in adding the page size
> calculation to the init code..

I forgot to mention the style bugs in the comment related to page
sizes.  IIRC, the comment has many hard-coded magic numbers which are
only correct if the page size is 4K and the allocations start on page
boundaries, but pages can be almost any size and are 8K on some supported
arches, and I think allocations made by UMA are only aligned to a small
power of 2.  I think this allows a 9k buffer to be split across 4
4K-pages (e.g., 128+4096+4096+680) or across 3 8K-pages (128+8192+680).
Hardware might not like this.  Otherwise, non-page-aligned allocations
should make the page size irrelevant.

Bruce