On Mon, 29 Jan 2007, Andi Kleen wrote:
> On Thursday 25 January 2007 22:37, David Rientjes wrote:
> > Any leftover memory is allocated
> > to a final node unless the command-line ends with a comma.
>
> That sounds like syntactical vinegar and a nasty trap. Remember
> that venus probe that got lost because of a wrong comma.
> Can you find some nicer syntax for that please?
>
The only other appropriate syntax that comes to mind is perhaps a
command-line that ends with a 0. For example, numa=fake=2*512,0 would
allocate two 512M nodes and nothing for the remaining RAM.
> Also it's pretty complex. Are there use cases for all of this?
>
There are. Configurable node sizes (i.e. 'numa=fake=512,4*128', etc) are
the major concept and help to avoid the overhead associated with something
like 64 nodes of 64M each on a 4G machine. We've seen some inefficiencies
with scanning through so many zone lists on page_alloc when we encounter a
full node. Additional support such as 'numa=fake=2*512,*128' are used
more for machines where you're unsure of their total system RAM in the
first place but want to make sure you have the node sizes you need.
David
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