From: akpm@linux-foundation.org Subject: + ext4-allocate-s_blockgroup_lock-separately.patch added to -mm tree Date: Tue, 18 Nov 2008 21:29:42 -0800 Message-ID: <200811190529.mAJ5TgKc016488@imap1.linux-foundation.org> Cc: penberg@cs.helsinki.fi, adilger@sun.com, linux-ext4@vger.kernel.org To: mm-commits@vger.kernel.org Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:55988 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750747AbYKSF3r (ORCPT ); Wed, 19 Nov 2008 00:29:47 -0500 Sender: linux-ext4-owner@vger.kernel.org List-ID: The patch titled ext4: allocate ->s_blockgroup_lock separately has been added to the -mm tree. Its filename is ext4-allocate-s_blockgroup_lock-separately.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: ext4: allocate ->s_blockgroup_lock separately From: Pekka Enberg As spotted by kmemtrace, struct ext4_sb_info is 17664 bytes on 64-bit which makes it a very bad fit for SLAB allocators. The culprit of the wasted memory is ->s_blockgroup_lock which can be as big as 16 KB when NR_CPUS >= 32. To fix that, allocate ->s_blockgroup_lock, which fits nicely in a order 2 page in the worst case, separately. This shinks down struct ext4_sb_info enough to fit a 2 KB slab cache so now we allocate 16 KB + 2 KB instead of 32 KB saving 14 KB of memory. Cc: Andreas Dilger Signed-off-by: Pekka Enberg Cc: Signed-off-by: Andrew Morton --- fs/ext4/ext4_sb.h | 4 ++-- fs/ext4/super.c | 10 +++++++++- 2 files changed, 11 insertions(+), 3 deletions(-) diff -puN fs/ext4/ext4_sb.h~ext4-allocate-s_blockgroup_lock-separately fs/ext4/ext4_sb.h --- a/fs/ext4/ext4_sb.h~ext4-allocate-s_blockgroup_lock-separately +++ a/fs/ext4/ext4_sb.h @@ -62,7 +62,7 @@ struct ext4_sb_info { struct percpu_counter s_freeinodes_counter; struct percpu_counter s_dirs_counter; struct percpu_counter s_dirtyblocks_counter; - struct blockgroup_lock s_blockgroup_lock; + struct blockgroup_lock *s_blockgroup_lock; struct proc_dir_entry *s_proc; /* root of the per fs reservation window tree */ @@ -150,7 +150,7 @@ struct ext4_sb_info { static inline spinlock_t * sb_bgl_lock(struct ext4_sb_info *sbi, unsigned int block_group) { - return bgl_lock_ptr(&sbi->s_blockgroup_lock, block_group); + return bgl_lock_ptr(sbi->s_blockgroup_lock, block_group); } #endif /* _EXT4_SB */ diff -puN fs/ext4/super.c~ext4-allocate-s_blockgroup_lock-separately fs/ext4/super.c --- a/fs/ext4/super.c~ext4-allocate-s_blockgroup_lock-separately +++ a/fs/ext4/super.c @@ -497,6 +497,7 @@ static void ext4_put_super(struct super_ ext4_blkdev_remove(sbi); } sb->s_fs_info = NULL; + kfree(sbi->s_blockgroup_lock); kfree(sbi); return; } @@ -1891,6 +1892,13 @@ static int ext4_fill_super(struct super_ sbi = kzalloc(sizeof(*sbi), GFP_KERNEL); if (!sbi) return -ENOMEM; + + sbi->s_blockgroup_lock = + kzalloc(sizeof(struct blockgroup_lock), GFP_KERNEL); + if (!sbi->s_blockgroup_lock) { + kfree(sbi); + return -ENOMEM; + } sb->s_fs_info = sbi; sbi->s_mount_opt = 0; sbi->s_resuid = EXT4_DEF_RESUID; @@ -2199,7 +2207,7 @@ static int ext4_fill_super(struct super_ &sbi->s_inode_readahead_blks); #endif - bgl_lock_init(&sbi->s_blockgroup_lock); + bgl_lock_init(sbi->s_blockgroup_lock); for (i = 0; i < db_count; i++) { block = descriptor_loc(sb, logical_sb_block, i); _ Patches currently in -mm which might be from penberg@cs.helsinki.fi are fs-introduce-bgl_lock_ptr.patch repeatable-slab-corruption-with-ltp-msgctl08.patch linux-next.patch ext4-allocate-s_blockgroup_lock-separately.patch ext2-allocate-s_blockgroup_lock-separately.patch ext3-allocate-s_blockgroup_lock-separately.patch slab-leaks3-default-y.patch