Re: NFS performances

[Jan Stary <hans%stare.cz@localhost>]

On May 12 15:06:25, jlmuir%imca-cat.org@localhost wrote:
> On 5/12/14, 2:27 PM, Jan Stary wrote:
> > On May 12 14:17:33, jlmuir%imca-cat.org@localhost wrote:
> >> On 5/12/14, 10:03 AM, Emmanuel Dreyfus wrote:
> >>> Hello
> >>>
> >>> I have a NFS setup with both NetBSD 6 client and server over a
> >>> gigabit network. Theperformance seems week, even whle client, server
> >>> and network are almost idle.
> >>>
> >>> The test: time dd if=/dev/zero of=test bs=1024k count=100
> >>>
> >>> Done on the NFS server itself:
> >>>    5.31s real 0.00s user 0.39s system
> >>>
> >>> Done over NFS:
> >>>    9.82s real 0.00s user 0.12s system
> >>>
> >>> The overhead looks huge. This is a UDP mount with a 1500 bytes MTU,
> >>> ping is at 0.8 ms from a virtualized client, ang 0.28 ms for a
> >>> physical one.
> >>>
> >>> Are the numbers reasonable? Should I consider a 59% NFS overhead as
> >>> acceptable, or are there some parameters to tweak?
> >>
> >> Hi, Emmanuel.
> >>
> >> RHEL 5 machine writing to an NFS v3 mount over GigE (1500 MTU):
> >>    1.22s real 0.00s user 0.06s system
> >>
> >> That's way faster than even your local test.  So, I'd say your
> >> numbers do not seem reasonable.
> >
> > We don't have any kind of detail for this comparison to even make
> > sense.
> 
> Hi, Jan.
> 
> True, I was just trying to give something for comparison under the
> assumption that something was better than nothing.
> 
> > How exactly is the filesystem exported?
> 
> With the following options:
> 
>   rw,no_subtree_check,sync
> 
> > How exactly is it mounted?
> 
> With the following options:
> 
>   retry=1,bg,intr,noatime,nodev,nosuid,timeo=20
> 
> > In particular, is it async on linux?
> 
> It is not async, and both the NFS client and server are on Linux.

Ah, so it has absolutely nothing to do
with the NetBSD NFS server or the NetBSD NFS client.

> > Is it even the same server?
> 
> I'm not sure what you mean.  Do you mean is the NFS server running
> NetBSD 6 and the same NFS code as Emmanuel's?  No, the server is running
> on Linux.  But I was just trying to give a ballpark comparison showing
> that Emmanuel's setup wasn't even close, thus suggesting something
> wasn't right about it.

We don't know _anything_ about his server, his client,
your server, and your client. This comparison is empty.

> >> Have you already determined that the problem is with NFS, not the
> >> network
> >
> > What "problem"? I still don't get it: writing over a network is
> > considerably slower than _not_ writing over a network, sure.
> >
> >> (e.g. by using netperf or maybe just "time dd if=/dev/zero bs=1024k
> >> count=100 | ssh NFS_SERVER 'cat > test'")?
> >
> > Ech, this brings irelevant influences into your "measurement";
> > for example, how much of that time is spent by ssh encrypting and
> > compressing the data (which has nothing to do with your network
> > performance)?
> 
> That's true.  Note that I suggested netperf first.  Still, the
> dd-over-ssh thing was just a quick thing to try.  I wouldn't think
> encrypting the data would be that hard on the machine, and if the
> dd-over-ssh thing was grossly faster, it would suggest that something
> was definitely wrong with the NFS setup.
> 
> Lewis