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Subject: Re: [lustre-devel] [PATCH] staging: lustre: delete the filesystem
 from the tree.
From:   Alexey Lyashkov <alexey.lyashkov@gmail.com>
In-Reply-To: <87h8mjp5o0.fsf@notabene.neil.brown.name>
Date:   Mon, 4 Jun 2018 06:59:45 +0300
Cc:     "Dilger, Andreas" <andreas.dilger@intel.com>,
        Andreas Dilger <adilger@dilger.ca>,
        "devel@driverdev.osuosl.org" <devel@driverdev.osuosl.org>,
        "Drokin, Oleg" <oleg.drokin@intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Christoph Hellwig <hch@infradead.org>,
        "selinux@tycho.nsa.gov" <selinux@tycho.nsa.gov>,
        fsdevel <linux-fsdevel@vger.kernel.org>,
        lustre-devel <lustre-devel@lists.lustre.org>
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Message-Id: <FE290581-D17D-4CEC-9AE2-B79DCBBD0823@gmail.com>
References: <20180601091133.GA27521@kroah.com>
 <20180601114151.GA25225@infradead.org>
 <E5BF8501-35EB-4DDF-ADBE-6016CF31A502@dilger.ca>
 <29ACF5A8-7608-46BB-8191-E3FEB77D0F24@cray.com>
 <87h8mmrt6b.fsf@notabene.neil.brown.name>
 <58123CDD-8424-4E1D-A11F-0F899970A49B@intel.com>
 <87h8mjp5o0.fsf@notabene.neil.brown.name>
To:     NeilBrown <neilb@suse.com>
Sender: linux-kernel-owner@vger.kernel.org
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> 4 =D0=B8=D1=8E=D0=BD=D1=8F 2018 =D0=B3., =D0=B2 6:54, NeilBrown =
<neilb@suse.com> =D0=BD=D0=B0=D0=BF=D0=B8=D1=81=D0=B0=D0=BB(=D0=B0):
>=20
> On Sun, Jun 03 2018, Dilger, Andreas wrote:
>=20
>> On Jun 1, 2018, at 17:19, NeilBrown <neilb@suse.com> wrote:
>>>=20
>>> On Fri, Jun 01 2018, Doug Oucharek wrote:
>>>=20
>>>> 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?
>>>=20
>>> 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).
>>>=20
>>> 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.
>>=20
>> LNet is originally based on a high-performance networking stack =
called
>> Portals (v3, http://www.cs.sandia.gov/Portals/), with additions for =
LNet
>> routing to allow cross-network bridging.
>>=20
>> A critical part of LNet is that it is for RDMA and not packet-based
>> messages.  Everything in Lustre is structured around RDMA.  Of =
course,
>> RDMA is not possible with TCP

To be clear. Soft IB (aka Soft RoCE) driver is part of OFED stack from =
4.8(or 4.9).
So RDMA API now is possible with TCP networks.


Alex=