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 <k-mio@xxxxxxxxxxxxx> --- 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) { -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
