percpu: implement kernel memory based chunk allocation
Implement an alternate percpu chunk management based on kernel memeory
for nommu SMP architectures. Instead of mapping into vmalloc area,
chunks are allocated as a contiguous kernel memory using
alloc_pages(). As such, percpu allocator on nommu will have the
following restrictions.
* It can't fill chunks on-demand page-by-page. It has to allocate
each chunk fully upfront.
* It can't support sparse chunk for NUMA configurations. SMP w/o mmu
is crazy enough. Let's hope no one does NUMA w/o mmu. :-P
* If chunk size isn't power-of-two multiple of PAGE_SIZE, the
unaligned amount will be wasted on each chunk. So, archs which use
this better align chunk size.
For instructions on how to use this, read the comment on top of
mm/percpu-km.c.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Cc: Graff Yang <graff.yang@gmail.com>
Cc: Sonic Zhang <sonic.adi@gmail.com>
diff --git a/mm/percpu.c b/mm/percpu.c
index 15f6804..39f7dfd 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -654,7 +654,11 @@
static struct page *pcpu_addr_to_page(void *addr);
static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai);
+#ifdef CONFIG_NEED_PER_CPU_KM
+#include "percpu-km.c"
+#else
#include "percpu-vm.c"
+#endif
/**
* pcpu_chunk_addr_search - determine chunk containing specified address
