Re: Need help debugging NFS issues new to 4.20 kernel

Benjamin Coddington
2019-02-06T12:05:53Z

On 5 Feb 2019, at 13:12, Jason Tibbitts wrote:

>>>>>> "JLT" == Jason L Tibbitts <tibbs@math.uh.edu> writes:
>
> JLT> I wonder, though; is that likely to be the root of the problem I'm
> JLT> seeing? The commit description talks about this as a performance
> JLT> regression, but I'm seeing a complete loss of NFS functionality.
>
> It turns out that 4.20.6 (which has the patch in question) does not
> appear to solve my issue. At least, I've still had a few complete NFS
> hangups on machines running 4.20.6 though I haven't had a chance to
> closely inspect one yet.
>
> As before, any hints about how I could best debug this issue would be
> appreciated.

Hi Jason, you can enable the NFS and SUNRPC tracepoints to get a better idea
of what the client was doing right before the hang or what the client is
trying to do during the hang:

echo "sunrpc:*" >> /sys/kernel/debug/tracing/set_event
echo "nfs:*" >> /sys/kernel/debug/tracing/set_event

Examine or provide the contents of /sys/kernel/debug/tracing/trace.

Ben