quoted

I'll try a more varied set of tests tonight, with cpu usage tabulated.

Please do a few non-swap tests too. 

Swapping is the thing that rmap is supposed to _help_, so improvements in
that area are good (and had better happen!), but if you're only looking at
the swap performance, you're ignoring the known problems with rmap, ie the
cases where non-rmap kernels do really well.

Comparing one but not the other doesn't give a very balanced picture..

It would also be interesting to see memory consumption figures for a benchmark 
with many large processes. With this type of load, memory consumption 
through PTEs is already a problem - as far as I can see, rmap triples the 
memory requirement of PTEs through the PTE chain's doubly linked list 
(an additional 8 bytes per entry) ... perhaps my calculations are wrong?  
This is particular problem for databases that tend to have thousands of
processes attatched to a large shared memory area.

A quick rough calculation indicates that the Oracle test I was helping out 
with was consuming almost 10Gb of PTEs without rmap - 30Gb for overhead 
doesn't sound like fun to me ;-(

M.


--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/