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List:       ceph-devel
Subject:    RE: Question about Transaction::get_data_alignment
From:       "Chen, Xiaoxi" <xiaoxi.chen () intel ! com>
Date:       2014-11-25 8:12:16
Message-ID: 6F3FA899187F0043BA1827A69DA2F7CC02105B62 () shsmsx102 ! ccr ! corp ! intel ! com
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Hi Sage,

       I think I have make a draft of this patch, could you pls kindly take a review \
at https://github.com/xiaoxichen/ceph/commit/983a36be52d4ddd17133979c17b25e9e319a5dad \
?

      By "streamline the encode path for these messages", do you mean we can do \
something like below so we can skip the initialize of some fields?  
               MOSDClientSubOp(ALL_ARGS_NEED_TO_SEND)
    : Message(MSG_OSD_CLIENT_SUBOP, HEAD_VERSION, COMPAT_VERSION)
    {
              encode_payload(uint64_t features, ALL_ARGS_NEED_TO_SEND) ;
    }

													Xiaoxi

-----Original Message-----
From: ceph-devel-owner@vger.kernel.org [mailto:ceph-devel-owner@vger.kernel.org] On \
                Behalf Of Sage Weil
Sent: Friday, November 21, 2014 9:33 AM
To: Chen, Xiaoxi
Cc: jianpeng; ceph-devel@vger.kernel.org; Cook, Nigel
Subject: RE: Question about Transaction::get_data_alignment

On Fri, 21 Nov 2014, Chen, Xiaoxi wrote:
> Hi,
> I have cleanup the MOSDClientSubOP and changed the issue_op. The receive side is \
> still wip. Sorry for the slow progress since blocked by a customer support case for \
> some weeks.  Here is the brunch to see if I goes on the right path.
> 
> https://github.com/xiaoxichen/ceph/commit/621c2a7dc2bc9724e9d2106b52aa
> 9eedd2c793e8

Yep, this looks like the right direction!

Once the reply path is in place, I think there are some things we can do to \
streamline the encode path for these messages (by, e.g., passing everything to the \
constructor and encoding directly there instead of copying into member variables and \
then encoding).  Let's start with something simple first, though.

Thanks-
sage

 > 
> -----Original Message-----
> From: Sage Weil [mailto:sage@newdream.net]
> Sent: Friday, November 21, 2014 1:30 AM
> To: Chen, Xiaoxi
> Cc: jianpeng; ceph-devel@vger.kernel.org; Cook, Nigel
> Subject: RE: Question about Transaction::get_data_alignment
> 
> Hi Xiaoxi,
> 
> Just wanted to touch base and see how things are going here.  I have some time to \
> spend on this and the related efforts so please let me know if you have any \
> questions or if you have some work-in-progress code I can help review. 
> Thanks!
> sage
> 
> 
> On Thu, 6 Nov 2014, Chen, Xiaoxi wrote:
> 
> > Hi Sage,
> > As discussed with Jianpeng, I would like to take this job.
> > Thank you.
> > 				Xiaoxi
> > 
> > -----Original Message-----
> > From: ceph-devel-owner@vger.kernel.org 
> > [mailto:ceph-devel-owner@vger.kernel.org] On Behalf Of Sage Weil
> > Sent: Wednesday, November 5, 2014 9:20 PM
> > To: jianpeng
> > Cc: ceph-devel@vger.kernel.org
> > 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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> > 
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