[Ocfs2-devel] [Patch] We resolve the throughput drop problem when r eading filesin OCFS2 volume in the patch "ocfs2-truncate-pages-1.patch" aga instsvn 1226.

[Wim Coekaerts]

very interesting !  ll hav to study this one closely :)
thanks !

On Thu, Jul 01, 2004 at 10:39:07AM +0800, Zhang, Sonic wrote:
> 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
> *********************************************  


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