Re: [Lhns-devel] Re: Who's doing what with cpu/memory/node hotplug?

Jesse Barnes
2004-05-17T23:36:48Z

On Monday, May 17, 2004 4:28 pm, Dave Hansen wrote:
> > Is anyone doing anything to optimize access to such beasts? Binding
> > processes that are accessing such I/O devices to nearby nodes ...
> > sounds possible for NIC, and ugly for disks.
>
> Well, binding isn't the best thing to do, but simple preference and
> error recovery would be great. The NUMAQ (and I'm sure others) used to
> have a few fiber channel cards in each node that allowed multiple paths
> to I/O devices. You could be fast, and recover from errors since
> everything was multiply connected. We do this on some drivers today,
> but not everything.

We do a few more things on Altix. IRQs are already routed to close CPUs, and
I have patches to allocate DMA memory from the node closest to a given
devices. Drivers can use pci_to_nodemask (currently pcibus_to_cpumask) to
get a list of nodes close to their device, and there are patches floating
about to link PCI busses to nodes in /sys, which would allow user level
applications to intelligently place themselves.

Jesse