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From: Benjamin Herrenschmidt on 10 May 2010 02:40
On Sat, 2010-05-08 at 08:17 -0700, Yinghai Lu wrote:
> It will return free memory size in specified range.
>
> We can not use memory_size - reserved_size here, because some reserved area
> may not be in the scope of lmb.memory.region.
>
> Use lmb.memory.region subtracting lmb.reserved.region to get free range array.
> then count size of all free ranges.

The name sucks. Something like lmb_free_memory_in_range() would be
better, but why do you need that in the first place ? You often tend to
fail to explain why you introduce a given function, it's not always
obvious and in many case I suspect they are added layers that aren't
actually useful.

Cheers,
Ben.

> Signed-off-by: Yinghai Lu <yinghai(a)kernel.org>
> ---
> include/linux/lmb.h | 1 +
> mm/lmb.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 52 insertions(+), 0 deletions(-)
>
> diff --git a/include/linux/lmb.h b/include/linux/lmb.h
> index c75d0c9..22be96d 100644
> --- a/include/linux/lmb.h
> +++ b/include/linux/lmb.h
> @@ -101,6 +101,7 @@ int get_free_all_memory_range(struct range **rangep, int nodeid);
> void lmb_register_active_regions(int nid, unsigned long start_pfn,
> unsigned long last_pfn);
> u64 lmb_hole_size(u64 start, u64 end);
> +u64 lmb_free_memory_size(u64 addr, u64 limit);
>
> #include <asm/lmb.h>
>
> diff --git a/mm/lmb.c b/mm/lmb.c
> index 36b3f63..4bc125c 100644
> --- a/mm/lmb.c
> +++ b/mm/lmb.c
> @@ -746,6 +746,57 @@ void __init lmb_to_bootmem(u64 start, u64 end)
> }
> #endif
>
> +u64 __init lmb_free_memory_size(u64 addr, u64 limit)
> +{
> + int i, count;
> + struct range *range;
> + int nr_range;
> + u64 final_start, final_end;
> + u64 free_size;
> +
> + count = lmb.reserved.cnt * 2;
> +
> + range = find_range_array(count);
> + nr_range = 0;
> +
> + addr = PFN_UP(addr);
> + limit = PFN_DOWN(limit);
> +
> + for (i = 0; i < lmb.memory.cnt; i++) {
> + struct lmb_property *r = &lmb.memory.region[i];
> +
> + final_start = PFN_UP(r->base);
> + final_end = PFN_DOWN(r->base + r->size);
> + if (final_start >= final_end)
> + continue;
> + if (final_start >= limit || final_end <= addr)
> + continue;
> +
> + nr_range = add_range(range, count, nr_range, final_start, final_end);
> + }
> + subtract_range(range, count, 0, addr);
> + subtract_range(range, count, limit, -1ULL);
> + for (i = 0; i < lmb.reserved.cnt; i++) {
> + struct lmb_property *r = &lmb.reserved.region[i];
> +
> + final_start = PFN_DOWN(r->base);
> + final_end = PFN_UP(r->base + r->size);
> + if (final_start >= final_end)
> + continue;
> + if (final_start >= limit || final_end <= addr)
> + continue;
> +
> + subtract_range(range, count, final_start, final_end);
> + }
> + nr_range = clean_sort_range(range, count);
> +
> + free_size = 0;
> + for (i = 0; i < nr_range; i++)
> + free_size += range[i].end - range[i].start;
> +
> + return free_size << PAGE_SHIFT;
> +}
> +
> u64 __init __weak __lmb_find_area(u64 ei_start, u64 ei_last, u64 start, u64 end,
> u64 size, u64 align)
> {


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