Messages in this thread Patch in this message | | | From | Namhyung Kim <> | Subject | [PATCH] ida: document IDA_BITMAP_LONGS calculation | Date | Fri, 3 Sep 2010 18:38:18 +0900 |
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IDA_BITMAP_LONGS value is calculated take into account struct ida_bitmap not to waste memory space. Comment it.
Signed-off-by: Namhyung Kim <namhyung@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> --- include/linux/idr.h | 5 ++++- 1 files changed, 4 insertions(+), 1 deletions(-)
diff --git a/include/linux/idr.h b/include/linux/idr.h index e968db7..3f4b718 100644 --- a/include/linux/idr.h +++ b/include/linux/idr.h @@ -117,10 +117,13 @@ void idr_init(struct idr *idp); /* * IDA - IDR based id allocator, use when translation from id to * pointer isn't necessary. + * + * IDA_BITMAP_LONGS is calculated to be one less to accommodate + * ida_bitmap->nr_busy so that the whole struct fits in 128 bytes. */ #define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */ #define IDA_BITMAP_LONGS (128 / sizeof(long) - 1) -#define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8) +#define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8) struct ida_bitmap { long nr_busy; -- 1.7.2.2
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