Re: [PATCH] pnfsblock: Lookup list entry of layouts and tags in reverse order

["J. Bruce Fields" <bfields@fieldses.org>]

On Wed, May 12, 2010 at 04:28:12PM -0400, bfields wrote:
> On Wed, May 12, 2010 at 09:46:43AM +0300, Benny Halevy wrote:
> > On May. 10, 2010, 6:36 +0300, Zhang Jingwang <zhangjingwang-U4AKAne5IzAR5TUyvShJeg@public.gmane.org> wrote:
> > > Optimize for sequencial write. Layout infos and tags are organized by
> > > file offset. When appending data to a file whole list will be examined,
> > > which introduce notable performance decrease.
> > 
> > Looks good to me.
> > 
> > Fred, can you please double check?
> 
> I don't know if Fred's still up for reviewing block stuff?
> 
> I've been trying to keep up with at least some minimal testing, but not
> as well as I'd like.
> 
> The one thing I've noticed is that the connectathon general test has
> started failing right at the start with an IO error.  The last good
> version I tested was b5c09c21, which was based on 33-rc6.  The earliest
> bad version I tested was 419312ada, based on 34-rc2.  A quick look at
> network traces from the two traces didn't turn up anything obvious.  I
> haven't had the chance yet to look closer.

As of the latest (6666f47d), in my tests the client is falling back on
IO to the MDS and doing no block IO at all.  b5c09c21 still works, so
the problem isn't due to a change in the server I'm testing against.  I
haven't investigated any more closely.

--b.