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    SubjectRe: [PATCH 13/22] lmb: Add lmb_free_memory_size()
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    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@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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