Hi Sage,
As discussed with Jianpeng, I would like to take this job.
Thank you.
Xiaoxi
-----Original Message-----
From: ceph-devel-owner@xxxxxxxxxxxxxxx [mailto:ceph-devel-owner@xxxxxxxxxxxxxxx] On Behalf Of Sage Weil
Sent: Wednesday, November 5, 2014 9:20 PM
To: jianpeng
Cc: ceph-devel@xxxxxxxxxxxxxxx
Subject: Re: Question about Transaction::get_data_alignment
On Wed, 5 Nov 2014, jianpeng wrote:
> Dong Yuan <yuandong <at> unitedstack.com> writes:
>
> >
> > Hi Sage,
> >
> > I am now working with the BP osd: update Transaction encoding, but
> > the Transaction::get_data_alignment make me confused.
> >
> > This method give the alignment which is used by FileJournal to do
> > better buffer build. It calculate the alignment by largest_data_off
> > and get_data_offset() while the first is an offset of some object
> > and the second is an offset of the transaction encode result. I am
> > not sure there is any reason to do calculation between them.
> >
> > The code works fine, probably because any result is fine for
> > Transaction::get_data_alignment, while
> > FileJournal::prepare_single_write can use any alignment value to
> > build logical bufferlist.
> >
> > Can you give me some explanation? Thank you.
> >
>
> Hi, i send a pull request to reduce the memcopy cause by unalignment.
> https://github.com/ceph/ceph/pull/2803
> I think get_data_offset() should not care largest_data_off.
I finally got to testing this and it looks good. Pulled the patches manually into master. Sorry it took so long!
For the last two MOSDSubOp, I think those changes should be done as part of this ticket
http://tracker.ceph.com/issues/9961
which will replace the common client replication op to use a fresh message type that is properly optimized. Jianpeng, is this something you might be interested in working on? We talked with Haomai about it during CDS but I think he and Yuan Dong will be occupied with the ObjectStore::Transaction encoding first, and I would really like to see this done in time for hammer (jan 1f freeze).
Thanks!
sage
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