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x86-32, numa: Update remap allocator comments

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Now that remap allocator is cleaned up, update comments such that they
are in docbook function description format and reflect the actual
implementation.

Signed-off-by: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/1301955840-7246-15-git-send-email-tj@kernel.org
Acked-by: Yinghai Lu <yinghai@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
Tejun Heo 2011-04-05 00:24:00 +02:00 committed by H. Peter Anvin
parent 198bd06bbf
commit 993ba1585c
1 changed files with 42 additions and 14 deletions
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56
arch/x86/mm/numa_32.c
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@ -176,17 +176,31 @@ static void __init allocate_pgdat(int nid)
}
/*
* In the DISCONTIGMEM and SPARSEMEM memory model, a portion of the kernel
* virtual address space (KVA) is reserved and portions of nodes are mapped
* using it. This is to allow node-local memory to be allocated for
* structures that would normally require ZONE_NORMAL. The memory is
* allocated with alloc_remap() and callers should be prepared to allocate
* from the bootmem allocator instead.
* Remap memory allocator
*/
static unsigned long node_remap_start_pfn[MAX_NUMNODES];
static void *node_remap_end_vaddr[MAX_NUMNODES];
static void *node_remap_alloc_vaddr[MAX_NUMNODES];
/**
* alloc_remap - Allocate remapped memory
* @nid: NUMA node to allocate memory from
* @size: The size of allocation
*
* Allocate @size bytes from the remap area of NUMA node @nid. The
* size of the remap area is predetermined by init_alloc_remap() and
* only the callers considered there should call this function. For
* more info, please read the comment on top of init_alloc_remap().
*
* The caller must be ready to handle allocation failure from this
* function and fall back to regular memory allocator in such cases.
*
* CONTEXT:
* Single CPU early boot context.
*
* RETURNS:
* Pointer to the allocated memory on success, %NULL on failure.
*/
void *alloc_remap(int nid, unsigned long size)
{
void *allocation = node_remap_alloc_vaddr[nid];
@ -238,6 +252,28 @@ void resume_map_numa_kva(pgd_t *pgd_base)
}
#endif
/**
* init_alloc_remap - Initialize remap allocator for a NUMA node
* @nid: NUMA node to initizlie remap allocator for
*
* NUMA nodes may end up without any lowmem. As allocating pgdat and
* memmap on a different node with lowmem is inefficient, a special
* remap allocator is implemented which can be used by alloc_remap().
*
* For each node, the amount of memory which will be necessary for
* pgdat and memmap is calculated and two memory areas of the size are
* allocated - one in the node and the other in lowmem; then, the area
* in the node is remapped to the lowmem area.
*
* As pgdat and memmap must be allocated in lowmem anyway, this
* doesn't waste lowmem address space; however, the actual lowmem
* which gets remapped over is wasted. The amount shouldn't be
* problematic on machines this feature will be used.
*
* Initialization failure isn't fatal. alloc_remap() is used
* opportunistically and the callers will fall back to other memory
* allocation mechanisms on failure.
*/
static __init void init_alloc_remap(int nid)
{
unsigned long size, pfn;
@ -306,14 +342,6 @@ void __init initmem_init(void)
{
int nid;
/*
* When mapping a NUMA machine we allocate the node_mem_map arrays
* from node local memory. They are then mapped directly into KVA
* between zone normal and vmalloc space. Calculate the size of
* this space and use it to adjust the boundary between ZONE_NORMAL
* and ZONE_HIGHMEM.
*/
get_memcfg_numa();
numa_init_array();