From: Trond Myklebust <trondmy@hammerspace.com>
To: "chuck.lever@oracle.com" <chuck.lever@oracle.com>
Cc: "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH 1/2] SUNRPC: Fix up backchannel slot table accounting
Date: Wed, 17 Jul 2019 17:19:06 +0000 [thread overview]
Message-ID: <97e9839faef3d1bc901d4ced3d0cf2e0bf2a0bd1.camel@hammerspace.com> (raw)
In-Reply-To: <99A569FB-DD7F-4547-AB06-FEB5DABA8488@oracle.com>
On Wed, 2019-07-17 at 09:55 -0400, Chuck Lever wrote:
> Hi Trond-
>
> > On Jul 16, 2019, at 4:01 PM, Trond Myklebust <trondmy@gmail.com>
> > wrote:
> >
> > Add a per-transport maximum limit in the socket case, and add
> > helpers to allow the NFSv4 code to discover that limit.
>
> For RDMA, the number of credits is permitted to change during the
> life
> of the connection, so this is not a fixed limit for such transports.
This is defining a maximum value, which is used for backchannel session
slot negotiation.
>
> And, AFAICT, it's not necessary to know the transport's limit. The
> lesser of the NFS backchannel and RPC/RDMA reverse credit limit will
> be used.
The server needs to know how many requests it can send in parallel on
the back channel. If it sends too many, which it can and will do on
TCP, then we currently break the connection, and so callbacks end up
being dropped or missed altogether.
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com
next prev parent reply other threads:[~2019-07-17 17:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-16 20:01 [PATCH 1/2] SUNRPC: Fix up backchannel slot table accounting Trond Myklebust
2019-07-16 20:01 ` [PATCH 2/2] NFSv4: Don't use the zero stateid with layoutget Trond Myklebust
2019-07-17 13:55 ` [PATCH 1/2] SUNRPC: Fix up backchannel slot table accounting Chuck Lever
2019-07-17 17:19 ` Trond Myklebust [this message]
2019-07-17 18:12 ` Chuck Lever
2019-07-17 18:20 ` Trond Myklebust
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