From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:34543 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750736AbeFAXTz (ORCPT ); Fri, 1 Jun 2018 19:19:55 -0400 From: NeilBrown To: Doug Oucharek , Andreas Dilger Date: Sat, 02 Jun 2018 09:19:40 +1000 Cc: "devel\@driverdev.osuosl.org" , Oleg Drokin , Greg Kroah-Hartman , Linux Kernel Mailing List , Christoph Hellwig , "selinux\@tycho.nsa.gov" , fsdevel , lustre-devel Subject: Re: [lustre-devel] [PATCH] staging: lustre: delete the filesystem from the tree. In-Reply-To: <29ACF5A8-7608-46BB-8191-E3FEB77D0F24@cray.com> References: <20180601091133.GA27521@kroah.com> <20180601114151.GA25225@infradead.org> <29ACF5A8-7608-46BB-8191-E3FEB77D0F24@cray.com> Message-ID: <87h8mmrt6b.fsf@notabene.neil.brown.name> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" Sender: linux-fsdevel-owner@vger.kernel.org List-ID: --=-=-= Content-Type: text/plain On Fri, Jun 01 2018, Doug Oucharek wrote: > Would it makes sense to land LNet and LNDs on their own first? Get > the networking house in order first before layering on the file > system? I'd like to turn that question on it's head: Do we need LNet and LNDs? What value do they provide? (this is a genuine question, not being sarcastic). It is a while since I tried to understand LNet, and then it was a fairly superficial look, but I think it is an abstraction layer that provides packet-based send/receive with some numa-awareness and routing functionality. It sits over sockets (TCP) and IB and provides a uniform interface. That is almost a description of the xprt layer in sunrpc. sunrpc doesn't have routing, but it does have some numa awareness (for the server side at least) and it definitely provides packet-based send/receive over various transports - tcp, udp, local (unix domain), and IB. So: can we use sunrpc/xprt in place of LNet? How much would we need to enhance sunrpc/xprt for this to work? What hooks would be needed to implement the routing as a separate layer. If LNet is, in some way, much better than sunrpc, then can we share that superior functionality with our NFS friends by adding it to sunrpc? Maybe the answer to this is "no", but I think LNet would be hard to sell without a clear statement of why that was the answer. One reason that I would like to see lustre stay in drivers/staging (so I do not support Greg's patch) is that this sort of transition of Lustre to using an improved sunrpc/xprt would be much easier if both were in the same tree. Certainly it would be easier for a larger community to be participating in the work. Thanks, NeilBrown --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEG8Yp69OQ2HB7X0l6Oeye3VZigbkFAlsR1IwACgkQOeye3VZi gbmuWxAAmeiHWBGFeXsoL5nX2bx2Vw0CRQKDJIa8bLndEDRpjMxjisBXCuQ3vcTk eTdKbk5c0LNZ5TwKtn/sPLIGQRCleq+6yCW/8TKb98q95BxoAEudJAW8ra2oxRUQ qDxfGKr/ytQkkDswxITsxYGNb1JThX0ajvS0DHzlwzzlrMgA7Ebwj9PJqRsCks8C QDfLN4q+wee5DMbpYlfkEcZsbUl2FS6igq92W4+QO0HhdTatpV0+17gXKLHey5pL os/PF7oD2rX8AXvu03GCjVp56jzxIUKiXZrAT1woSxqW/q4a/1v6o1PlgCQjaal0 ehVso1dZB2ZaU+VCI+x68sK+Fi3Kb3zPahhS43ot2zmZAypzMWhB2DYuPvby+r5J HbDbx1gun+tAMqahv8Bhd755NbskKqif30GXDqj16cPXJIN4NEM3Eb+1b+C6YCkN 5gQWAy1i2/PXyeMVUpt+fp98JN30mAVtdaeCmsn6V7mYDw3riAcbIFFs0jrij6aZ hMqDwySAksuad4+cJpE6K7WnYk4Af7ffa5jSPU4+nbdPZR3ogOqzqqmQKn928JuZ Ihp2Xu7RXddZ/+2lr5AOP9qe09K8T8iF7cB2aG/SZgHdwQJuaNPr4FISTyP5UjLc oR/pGNb6su9yRph6NBMjS0SgOb67LmMWCA1447RrbAHLM01d+hA= =VwDY -----END PGP SIGNATURE----- --=-=-=--