Subject: Re: [PATCH] Enable hashdist by default on 64bit NUMA

From: David Miller <[email-masked]>
Date: Thu, 26 Feb 2009 03:34:06 -0800 (PST)

From: Anton Blanchard <[email-masked]>
Date: Thu, 26 Feb 2009 22:24:32 +1100

> On PowerPC we allocate large boot time hashes on node 0. This leads to
> an imbalance in the free memory, for example on a 64GB box (4 x 16GB
> nodes):
> 
> Free memory:
> Node 0: 97.03%
> Node 1: 98.54%
> Node 2: 98.42%
> Node 3: 98.53%
> 
> If we switch to using vmalloc (like ia64 and x86-64) things are more
> balanced:
> 
> Free memory:
> Node 0: 97.53%
> Node 1: 98.35%
> Node 2: 98.33%
> Node 3: 98.33%
> 
> For many HPC applications we are limited by the free available memory on
> the smallest node, so even though the same amount of memory is used the
> better balancing helps.
> 
> Since all 64bit NUMA capable architectures should have sufficient
> vmalloc space, it makes sense to enable it via CONFIG_64BIT.
> 
> Signed-off-by: Anton Blanchard <[email-masked]>

Acked-by: David S. Miller <[email-masked]>