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| author | Jan Kara <jack@suse.cz> | 2013-04-29 15:06:17 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-04-29 15:54:28 -0700 |
| commit | 092c8d46e348b5fa4109a06d8a1246060e09dc8c (patch) | |
| tree | 2ef07a88ae3ed7638712a2fbcb9eb19ba0ece147 /fs/direct-io.c | |
| parent | e05c4bbfaedb7585a5b7936b3b84e68928c6474f (diff) | |
| download | lwn-092c8d46e348b5fa4109a06d8a1246060e09dc8c.tar.gz lwn-092c8d46e348b5fa4109a06d8a1246060e09dc8c.zip | |
direct-io: fix boundary block handling
When we read/write a file sequentially, we will read/write not only the
data blocks but also the indirect blocks that may not be physically
adjacent to the data blocks. So filesystems set the BH_Boundary flag to
submit the previous I/O before reading/writing an indirect block.
However the generic direct IO code mishandles buffer_boundary(), setting
sdio->boundary before each submit_page_section() call which results in
sending only one page bios as underlying code thinks this page is the last
in the contiguous extent. So fix the problem by setting sdio->boundary
only if the current page is really the last one in the mapped extent.
With this patch and "direct-io: submit bio after boundary buffer is added
to it" I've measured about 10% throughput improvement of direct IO reads
on ext3 with SATA harddrive (from 90 MB/s to 100 MB/s). With ramdisk, the
improvement was about 3-fold (from 350 MB/s to 1.2 GB/s). For other
filesystems (such as ext4), the improvements won't be as visible because
the frequency of BH_Boundary flag being set is much smaller.
Signed-off-by: Jan Kara <jack@suse.cz>
Reported-by: Kazuya Mio <k-mio@sx.jp.nec.com>
Tested-by: Kazuya Mio <k-mio@sx.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/direct-io.c')
| -rw-r--r-- | fs/direct-io.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/direct-io.c b/fs/direct-io.c index f853263cf74f..9644d0205dad 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -969,7 +969,8 @@ do_holes: this_chunk_bytes = this_chunk_blocks << blkbits; BUG_ON(this_chunk_bytes == 0); - sdio->boundary = buffer_boundary(map_bh); + if (this_chunk_blocks == sdio->blocks_available) + sdio->boundary = buffer_boundary(map_bh); ret = submit_page_section(dio, sdio, page, offset_in_page, this_chunk_bytes, |