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SubjectRe: [PATCH] ida: document IDA_BITMAP_LONGS calculation
On Fri, 3 Sep 2010, Namhyung Kim wrote:

> 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;

Tejun, any word on this patch? Doesn't seem to be present in linux-next.

Thanks,

--
Jiri Kosina
SUSE Labs, Novell Inc.


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