Messages in this thread | | | Date | Thu, 18 Mar 2004 15:32:27 -0800 | From | "Martin J. Bligh" <> | Subject | Re: [PATCH] Introduce nodemask_t ADT [0/7] |
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> On Thursday 18 March 2004 3:04 pm, Matthew Dobson wrote: >> do most anything you'd want to do with a nodemask. This stops us from >> open-coding nodemask operations, allows non-consecutive node numbering >> (ie: nodes don't have to be numbered 0...numnodes-1), gets rid of >> numnodes entirely (replaced with num_online_nodes()), and will >> facilitate the hotplugging of whole nodes. > > My hero! :) I think this has been needed for awhile, but now that I > think about it, it begs the question of what a node is. Is it a set > of CPUs and blocks of memory (that seems to be the most commonly used > definition in the code), just memory, just CPUs, or what? On sn2 > hardware, we have the concept of a node without CPUs. And due to our > wacky I/O layout, we also have nodes without CPUs *or* memory! (The > I/O guys call these "ionodes".) And then of course, there are CPUs > that aren't particularly close to any memory (i.e. they have none of > their own, and have to go several hops and/or through other CPUs to > get at memory at all).
I think the closest answer we have is that it's a grouping of cpus and memory, where either may be NULL.
I/O isn't directly associated with a node, though it should fit into the topo infrastructure, to give distances from io buses to nodes (for which I think we currently use cpumasks, which is probably wrong in retrospect, but then life is tough and flawed ;-))
M.
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