Messages in this thread Patch in this message | | | From | Xiaotian Feng <> | Subject | [RFC PATCH] block: slightly optimize blkdev_ioctl BLKRA{SET,GET} | Date | Tue, 14 Jul 2009 19:59:54 +0800 |
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Slightly optimize blkdev_ioctl by using shift instead of multiply and divide.
Signed-off-by: Xiaotian Feng <dfeng@redhat.com> --- block/ioctl.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/block/ioctl.c b/block/ioctl.c index 500e4c7..f8c7362 100644 --- a/block/ioctl.c +++ b/block/ioctl.c @@ -305,7 +305,7 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd, bdi = blk_get_backing_dev_info(bdev); if (bdi == NULL) return -ENOTTY; - return put_long(arg, (bdi->ra_pages * PAGE_CACHE_SIZE) / 512); + return put_long(arg, bdi->ra_pages << (PAGE_CACHE_SHIFT - 9)); case BLKROGET: return put_int(arg, bdev_read_only(bdev) != 0); case BLKBSZGET: /* get the logical block size (cf. BLKSSZGET) */ @@ -321,7 +321,7 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd, bdi = blk_get_backing_dev_info(bdev); if (bdi == NULL) return -ENOTTY; - bdi->ra_pages = (arg * 512) / PAGE_CACHE_SIZE; + bdi->ra_pages = arg >> (PAGE_CACHE_SHIFT - 9); return 0; case BLKBSZSET: /* set the logical block size */ -- 1.6.2.5
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