linux-kernel - [PATCH 0/2] nfsd: allow the use of multiple backchannel slots

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Message-Id: <20241028-bcwide-v1-0-0e75a8219dc0@kernel.org>
Date: Mon, 28 Oct 2024 10:26:25 -0400
From: Jeff Layton <jlayton@...nel.org>
To: Chuck Lever <chuck.lever@...cle.com>, Neil Brown <neilb@...e.de>, 
 Dai Ngo <Dai.Ngo@...cle.com>, Tom Talpey <tom@...pey.com>
Cc: Olga Kornievskaia <okorniev@...hat.com>, linux-nfs@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Jeff Layton <jlayton@...nel.org>
Subject: [PATCH 0/2] nfsd: allow the use of multiple backchannel slots

The NFSv4.1 server code has always only supported a single callback
slot. This has the effect of serializing all the callbacks on the
server, which can cause a bottleneck when there is a lot of callback
activity. This patchset allows the NFS server to use up to 32
backchannel slots when communicating with clients.

Note that so far, we don't have a great way to drive a lot of concurrent
backchannel activity with standard testsuites. I did set up a server
with two clients and had one client open a bunch of files, and a second
client fork off a bunch of processes that statx'ed those files
repeatedly. With that I was able to see the parallelization in action
via CB_GETATTR activity. I'm still thinking about how best to test this
with pynfs.

Signed-off-by: Jeff Layton <jlayton@...nel.org>
---
Jeff Layton (2):
      nfsd: remove nfsd4_session->se_bchannel
      nfsd: allow for more callback session slots

 fs/nfsd/nfs4callback.c | 107 +++++++++++++++++++++++++++++++++++--------------
 fs/nfsd/nfs4state.c    |   9 +++--
 fs/nfsd/state.h        |  13 +++---
 fs/nfsd/trace.h        |   2 +-
 4 files changed, 89 insertions(+), 42 deletions(-)
---
base-commit: c7b8826b41906db1c930cbb10abb94eb24247f20
change-id: 20241025-bcwide-6bd7e4b63db2

Best regards,
-- 
Jeff Layton <jlayton@...nel.org>