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

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

On Mon, May 17, 2010 at 05:24:39PM +0300, Boaz Harrosh wrote:
> On 05/17/2010 04:53 PM, J. Bruce Fields wrote:
> > 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.
> > 
> 
> You might be hitting the .commit bug, no? Still no fix. I'm using a work
> around for objects. I'm not sure how it affects blocks. I think you should
> see that the very first IO goes through layout driver then the IO is redone
> through MDS, for each node. Even though write/read returned success because
> commit returns NOT_ATTEMPTED. But I might be totally off.

I don't believe it's even attempting a GETLAYOUT.

I'll take a look at the network....--b.