Hi,
I have addressed Ted's comments.
(http://kerneltrap.org/mailarchive/linux-ext4/2009/7/3/6132903)
e2fsck_pass5() checks whether inode/block is consistency each. However, if
EXT2_BG_[INODE/BLOCK]_BITMAP is set to a ext4's block group, most of its bitmap
is uninitialized (0). In that case, e2fsck pass 5 becomes faster if it checks
consistency of uninitialized block group each 256 bytes.
This patch cuts e2fsck pass 5 time by up to 80%. The following results show the
e2fsck time.
Comparison of e2fsck time on an ext4 500GB partition (20% blocks used)
-------------------------------------------------
| | old e2fsck | new e2fsck |
|Pass | time(s) | time(s) |
| | real | user |system| real | user |system|
-------------------------------------------------
| 1 | 5.70| 3.29| 0.50| 5.66| 3.21| 0.54|
| 2 | 3.33| 0.80| 0.19| 3.40| 0.82| 0.23|
| 3 | 0.01| 0.00| 0.00| 0.01| 0.00| 0.00|
| 4 | 1.04| 1.04| 0.00| 1.05| 1.04| 0.00|
| 5 | 19.60| 17.27| 0.06| 3.53| 1.21| 0.05|
-------------------------------------------------
|Total| 29.94| 22.57| 0.80| 13.90| 6.47| 0.86|
-------------------------------------------------
Machine environment:
CPU: Intel(R) Xeon(TM) CPU 3.00GHz
Memory: 1GB
Kernel: linux-2.6.29-git2
e2fsprogs: 1.41.6
The following patch can be applied to e2fsprogs git tree (master branch).
Regards,
Kazuya Mio
Signed-off-by: Kazuya Mio <[email protected]>
---
e2fsck/pass5.c | 135 +++++++++++++++++++++++++++++++++++++-----------
lib/ext2fs/ext2fs.h | 2
lib/ext2fs/gen_bitmap.c | 94 +++++++++++++++++++++++++++++++++
3 files changed, 201 insertions(+), 30 deletions(-)
diff --git a/e2fsck/pass5.c b/e2fsck/pass5.c
index e660386..7c872d6 100644
--- a/e2fsck/pass5.c
+++ b/e2fsck/pass5.c
@@ -115,6 +115,11 @@ static void check_block_bitmaps(e2fsck_t ctx)
errcode_t retval;
int csum_flag;
int skip_group = 0;
+ int old_desc_blocks = 0;
+ int count = 0;
+ int cmp_block = 0;
+ int redo_flag = 0;
+ blk_t super_blk, old_desc_blk, new_desc_blk;
clear_problem_context(&pctx);
free_array = (int *) e2fsck_allocate_memory(ctx,
@@ -166,39 +171,82 @@ redo_counts:
actual = ext2fs_fast_test_block_bitmap(ctx->block_found_map, i);
if (skip_group) {
- blk_t super_blk, old_desc_blk, new_desc_blk;
- int old_desc_blocks;
-
- ext2fs_super_and_bgd_loc(fs, group, &super_blk,
+ if ((i - fs->super->s_first_data_block) %
+ fs->super->s_blocks_per_group == 0) {
+ super_blk = 0;
+ old_desc_blk = 0;
+ new_desc_blk = 0;
+ ext2fs_super_and_bgd_loc(fs, group, &super_blk,
&old_desc_blk, &new_desc_blk, 0);
- if (fs->super->s_feature_incompat &
- EXT2_FEATURE_INCOMPAT_META_BG)
- old_desc_blocks = fs->super->s_first_meta_bg;
- else
- old_desc_blocks = fs->desc_blocks +
+ if (fs->super->s_feature_incompat &
+ EXT2_FEATURE_INCOMPAT_META_BG)
+ old_desc_blocks =
+ fs->super->s_first_meta_bg;
+ else
+ old_desc_blocks = fs->desc_blocks +
fs->super->s_reserved_gdt_blocks;
+ }
bitmap = 0;
- if (i == super_blk)
- bitmap = 1;
- if (old_desc_blk && old_desc_blocks &&
- (i >= old_desc_blk) &&
- (i < old_desc_blk + old_desc_blocks))
- bitmap = 1;
- if (new_desc_blk &&
- (i == new_desc_blk))
- bitmap = 1;
- if (i == fs->group_desc[group].bg_block_bitmap)
+ if ((i == super_blk) ||
+ (old_desc_blk && old_desc_blocks &&
+ (i >= old_desc_blk) &&
+ (i < old_desc_blk + old_desc_blocks)) ||
+ (new_desc_blk && (i == new_desc_blk)) ||
+ (i == fs->group_desc[group].bg_block_bitmap) ||
+ (i == fs->group_desc[group].bg_inode_bitmap) ||
+ (i >= fs->group_desc[group].bg_inode_table &&
+ (i < fs->group_desc[group].bg_inode_table +
+ fs->inode_blocks_per_group))) {
bitmap = 1;
- else if (i == fs->group_desc[group].bg_inode_bitmap)
- bitmap = 1;
- else if (i >= fs->group_desc[group].bg_inode_table &&
- (i < fs->group_desc[group].bg_inode_table
- + fs->inode_blocks_per_group))
- bitmap = 1;
- actual = (actual != 0);
- } else
+ actual = (actual != 0);
+ count++;
+ } else if ((i - count - fs->super->s_first_data_block) %
+ fs->super->s_blocks_per_group == 0) {
+ /*
+ * Count the number of compare data blocks in
+ * every block group.The last block group's
+ * count is different, because that the last
+ * blockgroup is not saturation is possible.
+ */
+ if (group == (int)fs->group_desc_count - 1)
+ cmp_block = fs->super->s_blocks_count -
+ i +
+ fs->super->s_first_data_block;
+ else
+ cmp_block = fs->super->
+ s_blocks_per_group - count;
+
+ /*
+ * When the compare data blocks in block bitmap
+ * are 0, count the free block,
+ * skip the current block group.
+ */
+ if (ext2fs_test_zero_range(i, cmp_block,
+ (ext2fs_generic_bitmap)
+ ctx->block_found_map)) {
+ /*
+ * -1 means to skip the current block
+ * group.
+ */
+ blocks = fs->super->s_blocks_per_group
+ - 1;
+ group_free = cmp_block;
+ free_blocks += cmp_block;
+ /*
+ * The current block group's last block
+ * is set to i.
+ */
+ i += cmp_block - 1;
+ count = 0;
+ bitmap = 1;
+ goto do_counts;
+ }
+ }
+ } else if (redo_flag)
+ bitmap = actual;
+ else
bitmap = ext2fs_fast_test_block_bitmap(fs->block_map, i);
if (actual == bitmap)
@@ -291,6 +339,7 @@ redo_counts:
/* Redo the counts */
blocks = 0; free_blocks = 0; group_free = 0; group = 0;
memset(free_array, 0, fs->group_desc_count * sizeof(int));
+ redo_flag++;
goto redo_counts;
} else if (fixit == 0)
ext2fs_unmark_valid(fs);
@@ -342,6 +391,7 @@ static void check_inode_bitmaps(e2fsck_t ctx)
int problem, save_problem, fixit, had_problem;
int csum_flag;
int skip_group = 0;
+ int redo_flag = 0;
clear_problem_context(&pctx);
free_array = (int *) e2fsck_allocate_memory(ctx,
@@ -389,10 +439,34 @@ redo_counts:
/* Protect loop from wrap-around if inodes_count is maxed */
for (i = 1; i <= fs->super->s_inodes_count && i > 0; i++) {
+ bitmap = 0;
+ if (skip_group &&
+ i % fs->super->s_inodes_per_group == 1) {
+ /*
+ * Current inode is the first inode
+ * in the current block group.
+ */
+ if (ext2fs_test_zero_range(i,
+ fs->super->s_inodes_per_group,
+ (ext2fs_generic_bitmap)(ctx->inode_used_map))) {
+ /*
+ * When the compared inodes in inodes bitmap
+ * are 0, count the free inode,
+ * skip the current block group.
+ */
+ inodes = fs->super->s_inodes_per_group - 1;
+ group_free = inodes;
+ free_inodes += inodes;
+ i += inodes;
+ skip_group = 0;
+ goto do_counts;
+ }
+ }
+
actual = ext2fs_fast_test_inode_bitmap(ctx->inode_used_map, i);
- if (skip_group)
- bitmap = 0;
- else
+ if (redo_flag)
+ bitmap = actual;
+ else if (!skip_group)
bitmap = ext2fs_fast_test_inode_bitmap(fs->inode_map, i);
if (actual == bitmap)
goto do_counts;
@@ -496,6 +570,7 @@ do_counts:
dirs_count = 0; group = 0;
memset(free_array, 0, fs->group_desc_count * sizeof(int));
memset(dir_array, 0, fs->group_desc_count * sizeof(int));
+ redo_flag++;
goto redo_counts;
} else if (fixit == 0)
ext2fs_unmark_valid(fs);
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index 234fbdd..b011fb6 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -933,6 +933,8 @@ extern errcode_t
ext2fs_set_generic_bitmap_range(ext2fs_generic_bitmap bmap,
errcode_t magic,
__u32 start, __u32 num,
void *in);
+extern int ext2fs_test_zero_range(unsigned int start, unsigned int len,
+ ext2fs_generic_bitmap bitmap);
/* getsize.c */
extern errcode_t ext2fs_get_device_size(const char *file, int blocksize,
diff --git a/lib/ext2fs/gen_bitmap.c b/lib/ext2fs/gen_bitmap.c
index a1b1d8f..d699713 100644
--- a/lib/ext2fs/gen_bitmap.c
+++ b/lib/ext2fs/gen_bitmap.c
@@ -165,6 +165,100 @@ int ext2fs_test_generic_bitmap(ext2fs_generic_bitmap bitmap,
return ext2fs_test_bit(bitno - bitmap->start, bitmap->bitmap);
}
+/*
+ * Compare @mem to zero buffer by 256 bytes.
+ * Return 1 if @mem is zeroed memory, otherwise return 0.
+ */
+static int mem_is_zero(const char *mem, size_t len)
+{
+ static const char zero_buf[256];
+
+ while (len >= sizeof(zero_buf)) {
+ if (memcmp(mem, zero_buf, sizeof(zero_buf)))
+ return 0;
+ len -= sizeof(zero_buf);
+ mem += sizeof(zero_buf);
+ }
+ /* Deal with leftover bytes. */
+ if (len)
+ return !memcmp(mem, zero_buf, len);
+ return 1;
+}
+
+/*
+ * A specified district is checked in block bitmap or in inode bitmap.
+ */
+int ext2fs_test_zero_range(unsigned int start, unsigned int len,
+ ext2fs_generic_bitmap bitmap)
+{
+ size_t start_byte, len_byte = len >> 3;
+ int start_bit, len_bit = len % 8;
+ int first_bit = 0;
+ int last_bit = 0;
+ int mark_count = 0;
+ int mark_bit = 0;
+ int i;
+ const char *ADDR = bitmap->bitmap;
+
+ start -= bitmap->start;
+ start_byte = start >> 3;
+ start_bit = start % 8;
+
+ if (start_bit != 0) {
+ /*
+ * The compared start block number or start inode number
+ * is not the first bit in a byte.
+ */
+ mark_count = 8 - start_bit;
+ if (len < 8 - start_bit) {
+ mark_count = (int)len;
+ mark_bit = len + start_bit - 1;
+ } else
+ mark_bit = 7;
+
+ for (i = mark_count; i > 0; i--, mark_bit--)
+ first_bit |= 1 << mark_bit;
+
+ /*
+ * Compare blocks or inodes in the first byte.
+ * If there is any marked bit, this function returns 0.
+ */
+ if (first_bit & ADDR[start_byte])
+ return 0;
+ else if (len <= 8 - start_bit)
+ return 1;
+
+ start_byte++;
+ len_bit = (len - mark_count) % 8;
+ len_byte = (len - mark_count) >> 3;
+ }
+
+ /*
+ * The compared start block number or start inode number is
+ * the first bit in a byte.
+ */
+ if (len_bit != 0) {
+ /*
+ * The compared end block number or end inode number is
+ * not the last bit in a byte.
+ */
+ for (mark_bit = len_bit - 1; mark_bit >= 0; mark_bit--)
+ last_bit |= 1 << mark_bit;
+
+ /*
+ * Compare blocks or inodes in the last byte.
+ * If there is any marked bit, this function returns 0.
+ */
+ if (last_bit & ADDR[start_byte + len_byte])
+ return 0;
+ else if (len_byte == 0)
+ return 1;
+ }
+
+ /* Check whether all bytes are 0 */
+ return mem_is_zero(ADDR + start_byte, len_byte);
+}
+
int ext2fs_mark_generic_bitmap(ext2fs_generic_bitmap bitmap,
__u32 bitno)
{
On Thu, Jul 09, 2009 at 01:56:06PM +0900, Kazuya Mio wrote:
> Hi,
>
> I have addressed Ted's comments.
> (http://kerneltrap.org/mailarchive/linux-ext4/2009/7/3/6132903)
I fixed it up a bit before applying it. It turns out we already had a
function specific to block bitmaps, ext2fs_test_block_bitmap_range()
which provides this functionality. So I added the optimized version
of the generic bitmap test_range() function, and used it to speed up
ext2fs_test_block_bitmap_range(). This got placed into the maint branch.
The changes to e2fsck's pass5 has been checked into the 'master'
branch of e2fsprogs.
- Ted