max memory allocation

[Tim Wilde]

Joining the max memory allocation party a bit late...  regarding the
FreeBSD numbers, they depend entirely on your kernel's MAXDSIZ.  The 511M
result is typical with the standard MAXDSIZ of 512M.  With a MAXDSIZ of
1.5G:

FreeBSD 4.9-RELEASE-p4
max alloc = 1535 M

Current memcached is restricted by MAXDSIZ as well - even if you tell a
memcached process to use 2G, if your MAXDSIZ is 1.5G it'll only be able to
allocate 1.5G.

Oh, and playing with MAXDSIZ is not a fun thing to do.  On a box with 4G
physical RAM, I've had a hard time getting MAXDSIZ very far beyond 1.5G -
much above that and my kernel panics while booting.  Which is probably
just because I wasn't tuning all the right other bits, but it wasn't
important enough for me to mess with at the time.  It's not for the faint
of heart though.

Tim Wilde

-- 
Tim Wilde
twilde@dyndns.org
Systems Administrator
Dynamic Network Services, Inc.
http://www.dyndns.org/