- ridiculous-ext3-costs-was-re-page-fault-costs.patch removed from -mm tree
From: akpm@linux-foundation.org
Date: 2007-11-14 17:40:54
Also in:
mm-commits
The patch titled
ext3: mostly fix blobk bitmap read performance regression
has been removed from the -mm tree. Its filename was
ridiculous-ext3-costs-was-re-page-fault-costs.patch
This patch was dropped because it is obsolete
------------------------------------------------------
Subject: ext3: mostly fix blobk bitmap read performance regression
From: Linus Torvalds <torvalds@linux-foundation.org>
The ext3 block bitmap functions got added validation recently, which caused
a huge performance regression (ie 5x slower) due to very expensive modulus
calculations being done in a loop.
This largely fixes it, by moving the calculations out of the loop. The
sanity checking is still expensive, but no longer totally excessively so.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aneesh Kumar K.V <redacted>
Cc: Andreas Dilger <redacted>
Cc: Mingming Cao <redacted>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: <redacted>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
fs/ext3/balloc.c | 26 ++++++++++++++------------
1 file changed, 14 insertions(+), 12 deletions(-)
diff -puN fs/ext3/balloc.c~ridiculous-ext3-costs-was-re-page-fault-costs fs/ext3/balloc.c--- a/fs/ext3/balloc.c~ridiculous-ext3-costs-was-re-page-fault-costs
+++ a/fs/ext3/balloc.c@@ -80,12 +80,12 @@ struct ext3_group_desc * ext3_get_group_ return desc + offset; } -static inline int -block_in_use(ext3_fsblk_t block, struct super_block *sb, unsigned char *map) +static inline unsigned int +block_bit_number(__le32 block, struct super_block *sb) { - return ext3_test_bit ((block - - le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block)) % - EXT3_BLOCKS_PER_GROUP(sb), map); + __le32 first = EXT3_SB(sb)->s_es->s_first_data_block; + + return (le32_to_cpu(block) - le32_to_cpu(first)) % EXT3_BLOCKS_PER_GROUP(sb); } /**
@@ -102,6 +102,7 @@ static struct buffer_head * read_block_bitmap(struct super_block *sb, unsigned int block_group) { int i; + unsigned offset; struct ext3_group_desc * desc; struct buffer_head * bh = NULL; ext3_fsblk_t bitmap_blk;
@@ -120,20 +121,21 @@ read_block_bitmap(struct super_block *sb } /* check whether block bitmap block number is set */ - if (!block_in_use(bitmap_blk, sb, bh->b_data)) { + offset = block_bit_number(desc->bg_block_bitmap, sb); + if (!ext3_test_bit(offset, bh->b_data)) { /* bad block bitmap */ goto error_out; } /* check whether the inode bitmap block number is set */ - bitmap_blk = le32_to_cpu(desc->bg_inode_bitmap); - if (!block_in_use(bitmap_blk, sb, bh->b_data)) { + offset = block_bit_number(desc->bg_inode_bitmap, sb); + if (!ext3_test_bit(offset, bh->b_data)) { /* bad block bitmap */ goto error_out; } - /* check whether the inode table block number is set */ - bitmap_blk = le32_to_cpu(desc->bg_inode_table); - for (i = 0; i < EXT3_SB(sb)->s_itb_per_group; i++, bitmap_blk++) { - if (!block_in_use(bitmap_blk, sb, bh->b_data)) { + /* check whether the inode table block numbers are set */ + offset = block_bit_number(desc->bg_inode_table, sb); + for (i = 0; i < EXT3_SB(sb)->s_itb_per_group; i++, offset++) { + if (!ext3_test_bit(offset, bh->b_data)) { /* bad block bitmap */ goto error_out; }
_ Patches currently in -mm which might be from torvalds@linux-foundation.org are origin.patch revert-task-control-groups-example-cpu-accounting-subsystem.patch git-x86.patch ridiculous-ext3-costs-was-re-page-fault-costs.patch workaround-for-a-pci-restoring-bug.patch