LARGE single-system Cyrus installs?

[Andrew Morgan]

On Sat, 6 Oct 2007, Rob Mueller wrote:

> As it turns out, the memory leaks weren't critical, because the the pages do
> seem to be reclaimed when needed, though it was annoying not knowing exactly
> how much memory was really free/used. The biggest problem was that with
> cyrus you have millions of small files, and with a 32bit linux kernel the
> inode cache has to be in low memory, severely limiting how many files the OS
> will cache.
>
> See this blog post for the gory details, and why a 64-bit kernel was a nice
> win for us.
>
> http://blog.fastmail.fm/2007/09/21/reiserfs-bugs-32-bit-vs-64-bit-kernels-cache-vs-inode-memory/

Yesterday I checked my own Cyrus servers to see if I was running out of 
lowmem, and it sure looked like it.  Lowmem had only a couple MB free, and 
I had 2GB of free memory that was not being used for cache.

I checked again today and everything seems to be fine - 150MB of lowmem 
free and almost no free memory (3GB cached)!  Grrr.

Anyways, I was looking into building a 64-bit kernel.  I'm running Debian 
Sarge (I know, old) on a Dell 2850 with Intel Xeon (Nocona) CPUs and 4GB 
RAM.  My kernel version is 2.6.14.5, built from kernel.org sources.  It 
has "High Memory Support (64GB)" selected.

When I run menuconfig, I'm not seeing any obvious place to switch from 
32-bit to 64-bit.  Could you elaborate a bit about how you switched to a 
64-bit kernel?  Also, are you running a full 64-bit distro, or just a 
64-bit kernel?

Thanks,
 	Andy