percpu: allow non-linear / sparse cpu -> unit mapping
Currently cpu and unit are always identity mapped. To allow more
efficient large page support on NUMA and lazy allocation for possible
but offline cpus, cpu -> unit mapping needs to be non-linear and/or
sparse. This can be easily implemented by adding a cpu -> unit
mapping array and using it whenever looking up the matching unit for a
cpu.
The only unusal conversion is in pcpu_chunk_addr_search(). The passed
in address is unit0 based and unit0 might not be in use so it needs to
be converted to address of an in-use unit. This is easily done by
adding the unit offset for the current processor.
[ Impact: allows non-linear/sparse cpu -> unit mapping, no visible change yet ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index 63c8b7a..1e0e887 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -57,6 +57,7 @@
#endif
extern void *pcpu_base_addr;
+extern const int *pcpu_unit_map;
typedef void * (*pcpu_fc_alloc_fn_t)(unsigned int cpu, size_t size);
typedef void (*pcpu_fc_free_fn_t)(void *ptr, size_t size);
@@ -66,7 +67,7 @@
extern size_t __init pcpu_setup_first_chunk(
size_t static_size, size_t reserved_size,
ssize_t dyn_size, size_t unit_size,
- void *base_addr);
+ void *base_addr, const int *unit_map);
extern ssize_t __init pcpu_embed_first_chunk(
size_t static_size, size_t reserved_size,