Messages in this thread | | | Subject | Re: [PATCH] Introduce nodemask_t ADT [0/7] | From | Matthew Dobson <> | Date | Thu, 18 Mar 2004 15:58:32 -0800 |
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On Thu, 2004-03-18 at 15:23, Jesse Barnes wrote: > 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
Anything for a damsel in distress! ;)
> 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?
There have been arguments about exactly what a node is since there has been a concept of a node at all. In the kernel, it isn't defined. A node doesn't *have* to have CPUs on it (see nr_cpus_node()), doesn't *have* to have memory, doesn't *have* to have I/O. It's supposed to be just a container for those 3 things, but the containers can be empty. This code doesn't get into what a node is, just makes sure they're used properly... ;)
> 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".)
Yep... I saw both numnodes and numionodes perusing the ia64 code. You should be able to put these CPU/memless nodes in the node_online_map now... If there's code that's assuming a node contains either CPUs or memory, I'd like to find it! :)
> 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).
node_distance(from, to)
> I'll take a look at the ia64 bits when I get them (I've only received > two of the seven patches thus far). > > Jesse
Super. I'd really like feedback on the ia64 code (well, actually all the non-i386 code). I did what I thought was right, but eyes more familiar with the code are extremely welcome.
Cheers!
-Matt
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