[Ocfs2-devel] [Patch] We resolve the throughput drop problem when reading files in OCFS2 volume in the patch "ocfs2-truncate-pages-1.patch" against svn 1226.

[Zhang, Sonic]

Hi,

	We root caused the problem "The truncate_inode_page call in
ocfs_file_releasecauses the severethroughput drop of file reading in
OCFS2", which we put forward in our former mails. And now, we also
generate a patch to resolve this problem after one week debugging.

	This patch is against OCFS2 svn 1226.

	The average file reading throughput without our patch is 16
Mbtye/sec.
	The average file reading throughput with our patch is 1600
Mbtye/sec.
	Our patch has 100 times improvement on file reading throughput.
We will submit the full benchmark data of izone in the other mail soon.

	In our patch, we remove ocfs_truncate_pages() and
ocfs_extent_map_destroy() from routine ocfs_file_open() and
ocfs_file_release(), which enable file data page reuse between different
and sequential file access in one node. 

	In current OCFS2 design, file data consistency among all nodes
in the cluster is only ensured if this file is accessed in sequence. Our
patch keeps the same consistency level by a new vote request
FLAG_TRUNCATE_PAGES and a new vote action TRUNCATE_PAGES. This request
is broadcast when a file is asked to be opened for write. Then the
receivers truncate all in memory pages and extent maps of this file. The
sender truncates part of the pages and maps only when the file is
truncated (shortened).

	Please refer to the attachment.

	The throughput drop problem also occurs when creating, changing
and deleting directories on OCFS2 volume. But it is not covered in this
patch. We will work on the other patch to solve this problem.

	Any comments are appreciated.
	Thank you.



*********************************************
Sonic Zhang
Software Engineer
Intel China Software Lab
Tel: (086)021-52574545-1667
iNet: 752-1667
*********************************************  
-------------- next part --------------
A non-text attachment was scrubbed...
Name: ocfs2-truncate-pages-1.patch
Type: application/octet-stream
Size: 12209 bytes
Desc: ocfs2-truncate-pages-1.patch
Url : http://oss.oracle.com/pipermail/ocfs2-devel/attachments/20040701/16c155af/ocfs2-truncate-pages-1.obj