Messages in this thread | | | Date | Mon, 14 Apr 2003 10:22:46 -0700 | From | "Martin J. Bligh" <> | Subject | Re: Quick question about hyper-threading (also some NUMA stuff) |
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>> Ah, you probably don't want to do that ... it's very expensive. Moreover, >> if you exec 2ns later, all the effort will be wasted ... and it's very >> hard to deterministically predict whether you'll exec or not (stupid >> UNIX semantics). Doing it lazily is probably best, and as to "nodes >> would not have to reference the memory from others" - you're still >> doing that, you're just batching it on the front end. > > True... What about a vma-level COW-ahead just like we have a file-level > read-ahead, then? I mean batching the COW at unCOW-because-of-write time.
That'd be interesting ... and you can test that on a UP box, is not just NUMA. Depends on the workload quite heavily, I suspect.
> btw, COW-ahead sound really silly :)
Yeah. So be sure to call it that if it works out ... we need more things like that ;-) Moooooo. > Not possible for me since I've got no SMP. But posting a quick note about > your proposed "fake-NUMA-on-SMP.patch" would be good only if to have an > offsite (offbrain also? ;) backup of your ideas :)
Oh, well basically you just need to split memory in half, and assign one cpu to each "node" for each cpu_to_node thingy. Would be easy to just do it as static #defines for sizes at first (most of the work in supporting a new NUMA arch is just parsing the machinet tables). Set MAX_NUMNODES to > 1, make sure you create a pgdat for each "node", and frig with build_zonelists and free_area_init_core a bit.
M.
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