Re: [Lse-tech] Minutes from 4/5 Con Call

[Kanoj S. <kan...@ya...>]

.
> 	Kanoj examined Dan's approach fairly aggressivly 
> especially with regard to TLB and cacheline

True.

> utilization. Dan was 
> able to convince him it was the right way over the
> course of 
> dinner. 

Ummm, I seem to have given the wrong impression 
to Dan :-) I don't think it was quite
clear to me exactly how/what Dan's patch improves over
the current DISCONTIGMEM (possibly because I didn't
understand the implementation), as well as how it will
solve some of the problems associated with  virtually
contiguous but physically discontiguous chunks of
mem_maps. I did mention that Dan should talk to 
Davis Mossberger to understand why this approach was
tried and discarded on IA64 (other cpus might have
different enough characterstics to make this
approach performance safe). Some of the thought
process
that went into current DISCONTIGMEM is archived on
oss.sgi.com/projects/numa (well, I hope it still is
when oss comes back online!), but the set of 
restrictions that existed in the 2.3 timeframe might
have changed, allowing improvements.

I think DISCONTIGMEM should be looked as a feature
that allows laying out of chunked mem_map arrays
onto the chunks of physical memory they represent. 
There are possibly enough hooks to allow architectures

to chunk up their available physical memory in any
manner they wish (within reason). Agreed, this code
might not be pretty, and could be improved.

SGI folks, you should look closely at replacements
of DISCONTIGMEM, since DISCONTIG is used by mips64/SN0
and ia64/SN1. 

Kanoj




> 


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