NUMA memory support

Sun Oct 24 06:50:33 PDT 2004

On 24.10.2004, at 05:11, David Rhodus wrote:
The NUMA memory addressing support is built into the hardware, to be
specific the bios.  But to truly take advantage of NUMA the operating
system needs to differentiate things on the per-cpu bases.  The
per-cpu segmentation is a part of the fundamental design and
implementation of DragonFly. This allows for DragonFly to achieve
enhanced performance and greater reliability over other operating
systems.
But doesn't this for example mean that data originating from hardware 
(DMA) needs to be assigned to one CPU beforehand? For example, network 
packets somehow need to be assigned to the right CPU before they are 
evaluated, so that DMA will put them into the right memory area. 
Otherwise it could happen that a TCP packet arrives in CPU #1's memory, 
but gets dispatched to CPU #2's TCP thread (because of the connection 
hash). Now this thread needs to work on an mbuf that doesn't lie in 
local memory. Or am I complicating stuff?

cheers
  simon
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