Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752144Ab2FLJOX (ORCPT ); Tue, 12 Jun 2012 05:14:23 -0400 Received: from cantor2.suse.de ([195.135.220.15]:37666 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751182Ab2FLJOV (ORCPT ); Tue, 12 Jun 2012 05:14:21 -0400 Date: Tue, 12 Jun 2012 11:14:19 +0200 From: Jan Kara To: Akinobu Mita Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, Jan Kara , linux-ext4@vger.kernel.org Subject: Re: [PATCH v3 7/9] ext2: use memweight() Message-ID: <20120612091419.GC6021@quack.suse.cz> References: <1339203038-13069-1-git-send-email-akinobu.mita@gmail.com> <1339203038-13069-7-git-send-email-akinobu.mita@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1339203038-13069-7-git-send-email-akinobu.mita@gmail.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2790 Lines: 81 On Sat 09-06-12 09:50:36, Akinobu Mita wrote: > Convert ext2_count_free() to use memweight() instead of table lookup > based counting clear bits implementation. This change only affects > the code segments enabled by EXT2FS_DEBUG. > > Note that this memweight() call can't be replaced with a single > bitmap_weight() call, although the pointer to the memory area is > aligned to long-word boundary. Because the size of the memory area > may not be a multiple of BITS_PER_LONG, then it returns wrong value on > big-endian architecture. > > This also includes the following changes. > > - Remove unnecessary map == NULL check in ext2_count_free() which > always takes non-null pointer as the memory area. > > - Fix printk format warning that only reveals with EXT2FS_DEBUG. > > Signed-off-by: Akinobu Mita > Cc: Jan Kara Acked-by: Jan Kara Honza > Cc: linux-ext4@vger.kernel.org > --- > v3: rewrite to keep ext2_count_free() as a wrapper for memweight() > > fs/ext2/balloc.c | 14 ++------------ > fs/ext2/ialloc.c | 1 + > 2 files changed, 3 insertions(+), 12 deletions(-) > > diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c > index 1c36139..376aa77 100644 > --- a/fs/ext2/balloc.c > +++ b/fs/ext2/balloc.c > @@ -1444,19 +1444,9 @@ ext2_fsblk_t ext2_new_block(struct inode *inode, unsigned long goal, int *errp) > > #ifdef EXT2FS_DEBUG > > -static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0}; > - > -unsigned long ext2_count_free (struct buffer_head * map, unsigned int numchars) > +unsigned long ext2_count_free(struct buffer_head *map, unsigned int numchars) > { > - unsigned int i; > - unsigned long sum = 0; > - > - if (!map) > - return (0); > - for (i = 0; i < numchars; i++) > - sum += nibblemap[map->b_data[i] & 0xf] + > - nibblemap[(map->b_data[i] >> 4) & 0xf]; > - return (sum); > + return numchars * BITS_PER_BYTE - memweight(map->b_data, numchars); > } > > #endif /* EXT2FS_DEBUG */ > diff --git a/fs/ext2/ialloc.c b/fs/ext2/ialloc.c > index c13eb7b..8f370e01 100644 > --- a/fs/ext2/ialloc.c > +++ b/fs/ext2/ialloc.c > @@ -644,6 +644,7 @@ unsigned long ext2_count_free_inodes (struct super_block * sb) > } > brelse(bitmap_bh); > printk("ext2_count_free_inodes: stored = %lu, computed = %lu, %lu\n", > + (unsigned long) > percpu_counter_read(&EXT2_SB(sb)->s_freeinodes_counter), > desc_count, bitmap_count); > return desc_count; > -- > 1.7.7.6 > -- Jan Kara SUSE Labs, CR -- 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/