On Thu, Jan 19, 2006 at 06:08:08PM -0800, Paul Jackson wrote: > This compiles, but has not been tested past that. > Be more careful of this patch -- unlike the previous > two in this set, this patch reworks quite a bit of > the logic, so is at higher risk of being broken. > The first two work fine for me. This one is another case. With this, the bitmap_find_free_region() switches to walking the bitmap in 1 << order steps, as opposed to nbitsperlong, which causes it to skip over more space than it needs to and we end up fragmenting the bitmap pretty quickly. By changing bitmap_find_free_region() back to the previous behaviour, it seems to work again (at least in the bitmap_find_free_region() case). I hate to invalidate your comments this quickly, though :-) Signed-off-by: Paul Mundt <[email protected]> --- lib/bitmap.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/lib/bitmap.c b/lib/bitmap.c index 72bd06a..adf336e 100644 --- a/lib/bitmap.c +++ b/lib/bitmap.c @@ -687,7 +687,7 @@ EXPORT_SYMBOL(bitmap_bitremap); * depending on which combination of REG_OP_* flag bits is set. * * A region of a bitmap is a sequence of bits in the bitmap, of - * some size '1 << order' (a power of two), alligned to that same + * some size '1 << order' (a power of two), aligned to that same * '1 << order' power of two. * * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits). @@ -760,7 +760,7 @@ done: * * Find a region of free (zero) bits in a @bitmap of @bits bits and * allocate them (set them to one). Only consider regions of length - * a power (@order) of two, alligned to that power of two, which + * a power (@order) of two, aligned to that power of two, which * makes the search algorithm much faster. * * Return the bit offset in bitmap of the allocated region, @@ -768,9 +768,14 @@ done: */ int bitmap_find_free_region(unsigned long *bitmap, int bits, int order) { + int nbits_reg; /* number of bits in region */ + int nbitsinlong; /* num bits of region in each spanned long */ int pos; /* scans bitmap by regions of size order */ - for (pos = 0; pos < bits; pos += (1 << order)) + nbits_reg = 1 << order; + nbitsinlong = min(nbits_reg, BITS_PER_LONG); + + for (pos = 0; pos < bits; pos += nbitsinlong) if (__reg_op(bitmap, pos, order, REG_OP_ISFREE)) break; if (pos == bits)
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