From patchwork Sun Nov 25 00:36:29 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [1/6] libext2fs: optimize rb_set_bmap_range() Date: Sat, 24 Nov 2012 14:36:29 -0000 From: Theodore Ts'o X-Patchwork-Id: 201496 Message-Id: <1353803794-11593-2-git-send-email-tytso@mit.edu> To: Ext4 Developers List Cc: Theodore Ts'o This speeds up reading bitmaps from disk for very large (and full) disks by significant amounts (i.e., up to two CPU minutes for a 4T file system). Addresses-Google-Bug: #7534813 Signed-off-by: "Theodore Ts'o" --- lib/ext2fs/blkmap64_rb.c | 32 +++++++++++++++++++++++++++++--- 1 file changed, 29 insertions(+), 3 deletions(-) diff --git a/lib/ext2fs/blkmap64_rb.c b/lib/ext2fs/blkmap64_rb.c index a42eda1..816f44f 100644 --- a/lib/ext2fs/blkmap64_rb.c +++ b/lib/ext2fs/blkmap64_rb.c @@ -674,16 +674,42 @@ static errcode_t rb_set_bmap_range(ext2fs_generic_bitmap bitmap, __u64 start, size_t num, void *in) { struct ext2fs_rb_private *bp; + unsigned char *cp; size_t i; + int first_set = -1; int ret; bp = (struct ext2fs_rb_private *) bitmap->private; for (i = 0; i < num; i++) { - ret = ext2fs_test_bit(i, in); - if (ret) - rb_insert_extent(start + i - bitmap->start, 1, bp); + if (i & 7 == 0) { + unsigned char c = cp[i/8]; + if (c == 0xFF) { + if (first_set == -1) + first_set = i; + i += 7; + continue; + } + if ((c == 0x00) && (first_set == -1)) { + i += 7; + continue; + } + } + if (ext2fs_test_bit(i, in)) { + if (first_set == -1) + first_set = i; + continue; + } + if (first_set == -1) + continue; + + rb_insert_extent(start + first_set - bitmap->start, + i - first_set, bp); + first_set = -1; } + if (first_set != -1) + rb_insert_extent(start + first_set - bitmap->start, + num - first_set, bp); return 0; }