Re: [PATCH 1/5] cpuset memory spread basic implementation

[Andi Kleen <ak@suse.de>]

On Monday 06 February 2006 11:23, Ingo Molnar wrote:

> 
> well, if the pagecache is filled on a node above a certain ratio then 
> one would have to spread it out forcibly. 

In theory yes. In practice it doesn't work that well ...

> But otherwise, try to keep  
> things as local as possible, because that will perform best. 

Experience teaches differently. For IO caches (and d/icache) strict local 
caching doesn't seem to be the best policy because it competes with more
important mapped memory too much.

> This is  
> different from the case Paul's patch is addressing: workloads which are 
> known to be global (and hence spreading out is the best-performing 
> allocation).
> 
> (for which problem i suggested a per-mount/directory/file 
> locality-of-reference attribute in another post.)

iirc there is already a patch around for tmpfs to do that. But the 
interesting point here is what should be that default. And what
to do with the d/icaches by default.

-Andi