Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751964AbZGNL75 (ORCPT ); Tue, 14 Jul 2009 07:59:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751207AbZGNL75 (ORCPT ); Tue, 14 Jul 2009 07:59:57 -0400 Received: from mx2.redhat.com ([66.187.237.31]:52916 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751074AbZGNL74 (ORCPT ); Tue, 14 Jul 2009 07:59:56 -0400 From: Xiaotian Feng To: axboe@kernel.dk Cc: linux-kernel@vger.kernel.org, Xiaotian Feng Subject: [RFC PATCH] block: slightly optimize blkdev_ioctl BLKRA{SET,GET} Date: Tue, 14 Jul 2009 19:59:54 +0800 Message-Id: <1247572794-24107-1-git-send-email-dfeng@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1360 Lines: 38 Slightly optimize blkdev_ioctl by using shift instead of multiply and divide. Signed-off-by: Xiaotian Feng --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/