Re: [PATCH RFC 1/5] sched,numa: build table of node hop distance

[Rik van Riel]

On 10/12/2014 09:17 AM, Peter Zijlstra wrote:
> On Wed, Oct 08, 2014 at 03:37:26PM -0400, riel@xxxxxxxxxx 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.
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