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List:       linux-rdma
Subject:    NFSoRDMA bi-weekly developers meeting minutes (5/28/15)
From:       Shirley Ma <shirley.ma () oracle ! com>
Date:       2015-05-28 18:11:30
Message-ID: 55675A52.1010700 () oracle ! com
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Attendees:

Jeff Becker (NASA)
Yan Burman (Mellanox)
Chuck Lever (Oracle)
Rupert Dance (Soft Forge)
Steve Dickson (Red Hat)
Shirley Ma (Oracle)
Anna Schumaker (Net App)
Devesh Sharma (Avago Tech)

Today's meeting notes:

NFSoRDMA deployment (Jeff)
-------------------
NASA is interested in deployment NFS/RDMA, it's on the table.

NFSoRDMA RFC update (Chuck)
--------------------
Updating IETF specifications for RPC/RDMA (RGFC5666) and NFS/RDMA (RFC5667) to close \
the holes that might cause confusion. We'd like to replace RFC 5666 with a new \
document that fixes problems with the RPC/RDMA version 1 protocol; and replace RFC \
5667 with a new document that fills in missing or incorrect items with regard to \
NFSv4.0 and NFSv4.1 (and pNFS). There will be no protocol changes that would break \
backwards compatibility.

Chuck has published an experimental draft describing the conventions needed for \
bi-directional RPC/RDMA: \
https://datatracker.ietf.org/doc/draft-cel-nfsv4-rpcrdma-bidirection/

NFSoRDMA bi-directional implementation (Chuck)
---------------------------------------
Chuck has done an experimental implementation, which has been tested among Linux \
client, Linux server, Solaris client and Solaris server. NFS/RDMA bi-directional \
support is targeted in Linux 4.3 or 4.4, which might be available 6 months later.

Wireshark dissectors support RPC/RDMA, NFS/RDMA (Yan)
-----------------------------------------------
Yan and his team have been working on wireshark dissectors to support RPC/RDMA, \
NFS/RDMA. The patches will be submitted next week for review. This is a good news for \
debugging NFS/RDMA problems.

NFS/RDMA client and server shutdown issue (Nevesh, Shirley)
-----------------------------------------
Any outstanding mounts will prevent both client and server from shut down properly. \
The right fix is to handle CM_DEVICE_REMOVAL properly so the resources being \
allocated can be gracefully clean up. We can suggest umount before shutdown the \
client to avoid this issue, but on server side, we need to add a handler to handle \
outstanding cm_ids, which is not presented in current implementation.

NFSD workqueue mode vs. threading mode performance impacts: (Shirley)
---------------------------------------------------------------------
Shirley has spent sometime test/fix/evaluating NFSD workqueue mode originally \
implemented by Jeff Layton. NFSD workqueue patchset NFSD workqueue modes benefit some \
workloads while global threading mode benefits some other workloads. workqueue mode \
is better than per-cpu threading mode in general. workqueue is per-cpu workqueue \
while global threading mode is not per-cpu based. There might be some room to make \
NFSD workqueue not worse than global threading mode, but this requires to do more in \
depth performance investigation work.

Feel free to reply here for anything missing or incorrect. Thanks everyone for \
joining the call and providing valuable inputs/work to the community to make NFSoRDMA \
better.

Cheers,
Shirley
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