Messages in this thread |  | | Date | Tue, 14 Oct 2014 08:47:20 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH RFC 1/5] sched,numa: build table of node hop distance |
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On Sun, Oct 12, 2014 at 09:28:04AM -0400, Rik van Riel wrote: > On 10/12/2014 09:17 AM, Peter Zijlstra wrote: > >On Wed, Oct 08, 2014 at 03:37:26PM -0400, riel@redhat.com wrote: > >>+ sched_domains_numa_hops = kzalloc(sizeof(int) * nr_node_ids * nr_node_ids, GFP_KERNEL); > >>+ if (!sched_domains_numa_hops) > >>+ return; > > > >That's potentially a _BIG_ table (1M for a 512 node system). > >The node_distance has magic allocations and is of u8 size, is there any > >way we can re-use node_distance and avoid a second O(n^2) allocation? > > You are right, this should be a u8 at the least. > > Beyond that, I am not convinced that merging things into > the same array is worthwhile, since (IIRC) nr_node_ids > should be set to the actual number of nodes on the system > by then.
The thing is, it looks like all you do is compare hop distance, and the order of the hop distances is the exact same order as the regular numa distance. I could not find a place where you use the actual hop value.
So if all you're interested in is the relative ordering, that should be the same for both.
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