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Subject: Re: [PATCH 00/20] NFSD support for multiple RPC/RDMA chunks
From:   Chuck Lever <chuck.lever@oracle.com>
In-Reply-To: <20201028071601.GA114054@unreal>
Date:   Wed, 28 Oct 2020 09:10:42 -0400
Cc:     Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
        linux-rdma@vger.kernel.org
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Message-Id: <386B59D5-BBAB-464A-A37F-13290CBE51E6@oracle.com>
References: <160373843299.1886.12604782813896379719.stgit@klimt.1015granger.net>
 <20201027060823.GF4821@unreal>
 <DAC657D8-D254-452C-9B21-3053F70C8C73@oracle.com>
 <20201028071601.GA114054@unreal>
To:     Leon Romanovsky <leon@kernel.org>
Precedence: bulk


> On Oct 28, 2020, at 3:16 AM, Leon Romanovsky <leon@kernel.org> wrote:
>=20
> On Tue, Oct 27, 2020 at 09:24:54AM -0400, Chuck Lever wrote:
>> Hi Leon-
>>=20
>>> On Oct 27, 2020, at 2:08 AM, Leon Romanovsky <leon@kernel.org> =
wrote:
>>>=20
>>> On Mon, Oct 26, 2020 at 02:53:53PM -0400, Chuck Lever wrote:
>>>> This series implements support for multiple RPC/RDMA chunks per RPC
>>>> transaction. This is one of the few remaining generalities that the
>>>> Linux NFS/RDMA server implementation lacks.
>>>>=20
>>>> There is currently one known NFS/RDMA client implementation that =
can
>>>> send multiple chunks per RPC, and that is Solaris. Multiple chunks
>>>> are rare enough that the Linux NFS/RDMA implementation has been
>>>> successful without this support for many years.
>>>=20
>>> So why do we need it? Solaris is dead, and like you wrote Linux =
systems
>>> work without this feature just fine, what are the benefits? Who will =
use it?
>>=20
>> The Linux NFS implementation is living. We can add the ability
>> to provision multiple chunks per RPC to the Linux NFS client at
>> any time.
>>=20
>> Likewise any actively developed NFS/RDMA implementation can add
>> this feature. The RPC/RDMA version 1 protocol does not have the
>> ability to communicate the maximum number of chunks the server
>> will accept per RPC.
>>=20
>> Other server implementations do support multiple chunks per RPC.
>> The Linux NFS/RDMA server implementation has always been incomplete
>> in this regard.
>>=20
>> And the Linux NFS server implementation (the non-transport specific
>> part) already supports multiple data payloads per NFSv4 COMPOUND.
>=20
> Thanks, I just got different feeling then I read the cover letter.
> You presented it like no one needs this feature.

Understood. I'll incorporate a summary of the content of this thread
in the cover letter for the next version of the series.

--
Chuck Lever