Re: NFS/TCP timeouts

[Olga Kornievskaia <aglo@umich.edu>]

Hi Trond,

I'd like to raise this once again. Is this true that setting a timeout
limit (TCP_USER_TIMEOUT) is not user configurable (rather I'm pretty
sure it is not) but my question is why shouldn't it be tied to the
"timeo" mount option? Right now, only the sesson/lease manager thread
sets it via rpc_set_connect_timeout() to be lease period related.

Is it the fact that we don't want to allow user to control TCP
settings via the mount options? But somehow folks are expecting to be
able to set low "timeo" value and have the (dead) connection to be
considered dead earlier than for a rather long timeout period which is
happening now.

Thanks.

On Wed, Oct 3, 2018 at 3:06 PM Olga Kornievskaia <aglo@umich.edu> wrote:
>
> On Wed, Oct 3, 2018 at 2:45 PM Trond Myklebust <trondmy@hammerspace.com> wrote:
> >
> > On Wed, 2018-10-03 at 14:31 -0400, Olga Kornievskaia wrote:
> > > Hi folks,
> > >
> > > Is it true that NFS mount option "timeo" has nothing to do with the
> > > socket's setting of the user-specified timeout TCP_USER_TIMEOUT.
> > > Instead, when creating a TCP socket NFS uses either default/hard
> > > coded
> > > value of 60s for v3 or for v4.x it's lease based. Is there no value
> > > is
> > > having an adjustable TCP timeout value?
> > >
> >
> > It is adjusted. Please see the calculation in
> > xs_tcp_set_socket_timeouts().
>
> but it's not user configurable, is it? I don't see a way to modify
> v3's default 60s TCP timeout. and also in v4, the timeouts are set
> from xs_tcp_set_connect_timeout() for the lease period but again not
> user configurable, as far as i can tell.
>
> >
> > --
> > Trond Myklebust
> > Linux NFS client maintainer, Hammerspace
> > trond.myklebust@hammerspace.com
> >
> >