| Submitter | Theodore Ts'o |
|---|---|
| Date | Nov. 26, 2012, 4:39 p.m. |
| Message ID | <1353947981-15219-2-git-send-email-tytso@mit.edu> |
| Download | mbox | patch |
| Permalink | /patch/201726/ |
| State | Superseded |
| Headers | show |
Comments
On Mon, 26 Nov 2012, Theodore Ts'o wrote: > Date: Mon, 26 Nov 2012 11:39:35 -0500 > From: Theodore Ts'o <tytso@mit.edu> > To: Ext4 Developers List <linux-ext4@vger.kernel.org> > Cc: Theodore Ts'o <tytso@mit.edu> > Subject: [PATCH 1/6 -v2] libext2fs: optimize rb_set_bmap_range() > > 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 Looks good. Reviewed-by: Lukas Czerner <lczerner@redhat.com> > > Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> > --- > 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..0fc7c57 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 = in; > 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; > } > -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Patch
diff --git a/lib/ext2fs/blkmap64_rb.c b/lib/ext2fs/blkmap64_rb.c index a42eda1..0fc7c57 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 = in; 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; }
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" <tytso@mit.edu> --- lib/ext2fs/blkmap64_rb.c | 32 +++++++++++++++++++++++++++++--- 1 file changed, 29 insertions(+), 3 deletions(-)