Messages in this thread | | | Date | Tue, 22 Sep 2009 09:01:55 +0900 | From | Tejun Heo <> | Subject | Re: [PATCH 1/3] powerpc: Allocate per-cpu areas for node IDs for SLQB to use as per-node areas |
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Hello,
Mel Gorman wrote: > diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c > index 1f68160..a5f52d4 100644 > --- a/arch/powerpc/kernel/setup_64.c > +++ b/arch/powerpc/kernel/setup_64.c > @@ -588,6 +588,26 @@ void __init setup_per_cpu_areas(void) > paca[i].data_offset = ptr - __per_cpu_start; > memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start); > } > +#ifdef CONFIG_SLQB > + /* > + * SLQB abuses DEFINE_PER_CPU to setup a per-node area. This trick > + * assumes that ever node ID will have a CPU of that ID to match. > + * On systems with memoryless nodes, this may not hold true. Hence, > + * we take a second pass initialising a "per-cpu" area for node-ids > + * that SLQB can use > + */ > + for_each_node_state(i, N_NORMAL_MEMORY) { > + > + /* Skip node IDs that a valid CPU id exists for */ > + if (paca[i].data_offset) > + continue; > + > + ptr = alloc_bootmem_pages_node(NODE_DATA(cpu_to_node(i)), size); > + > + paca[i].data_offset = ptr - __per_cpu_start; > + memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start); > + } > +#endif /* CONFIG_SLQB */ > } > #endif
Eh... I don't know. This seems too hacky to me. Why not just allocate pointer array of MAX_NUMNODES and allocate per-node memory there? This will be slightly more expensive but I doubt it will be noticeable. The only extra overhead is the cachline footprint for the extra array.
Thanks.
-- tejun
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