Re: 4g/4g for 2.6.6

[Andrea Arcangeli <andrea@suse.de>]

On Tue, May 25, 2004 at 04:10:29PM -0400, Rik van Riel wrote:
> Fragmentation causes fork trouble (gone with the 4k stacks)

btw, the 4k stacks sounds not safe to me, most people only tested with
8k stacks so far, I wouldn't make that change in a production tree
without an unstable cycle of testing in between. I'd rather risk a
an allocation failure than a stack memory corruption.

x86-64 has per-irq stacks that allowed to reduce the stack size to 8k
(which is very similar to 4k for an x86, but without per-irq stack it's
too risky).

as for the dcache size, I can certainly imagine you can measure slowdown
bigger than 4:4 in some very vfs intensive workload, but the stuff that
needs 32G of ram normally uses only rawio or a few huge files as storage
anyways. as for the kiobufs they're long gone in 2.6.

Possibly some webserving could use 32G as pure pagecache for the
webserver with tons of tiny files, for such an app the 2:2 or 1:3 model
should be better than 4:4.