Date:   Tue, 30 Nov 2021 10:32:11 -0500
From:   Bruce Fields <bfields@fieldses.org>
To:     dai.ngo@oracle.com
Cc:     Chuck Lever III <chuck.lever@oracle.com>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH RFC v5 0/2] nfsd: Initial implementation of NFSv4
 Courteous Server
Message-ID: <20211130153211.GB8837@fieldses.org>
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On Mon, Nov 29, 2021 at 11:13:34PM -0800, dai.ngo@oracle.com wrote:
> Just to be clear, the problem of pynfs with 4.0 is that the server takes
> ~55 secs to expire 1026 4.0 courteous clients, which comes out to ~50ms
> per client. This causes the test to time out in waiting for RPC reply of
> the OPEN that triggers the conflicts.
> 
> I don't know exactly where the time spent in the process of expiring a
> client. But as Bruce mentioned, it could be related to the time to access
> /var/lib/nfs to remove the client's persistent record.

Could you try something like

	strace -r -$(pidof) -oTRACE

and maybe we could take a look at TRACE?  My hope would be that there'd
be a clear set of syscalls whose time, multiplied by 1026, explains most
of that 55 seconds.  Then it might be worth checking whether there are
any easy optimizations possible.

--b.