max memory allocation

Tim Wilde
Fri, 23 Apr 2004 22:19:50 -0400 (EDT)

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

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
Systems Administrator
Dynamic Network Services, Inc.