Mailinglist Archive: opensuse (3156 mails)

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Re: [opensuse] OpenSuse 10.2 - Fortran compilation very slow through NFS network with a 64bit server and 32bit clients.
  • From: Aaron Kulkis <akulkis00@xxxxxxxxxx>
  • Date: Fri, 30 Nov 2007 11:38:06 -0500
  • Message-id: <47503C6E.8080704@xxxxxxxxxx>
Dave Howorth wrote:
Michel Rasquin wrote:
Dear all,

I am a new OpenSuSE user and quite convinced by this distribution. However, I still have a problem.

I have configured a gigabit network, using nfs and everything works fine except for all the Fortran compilers I have tried so far (Intel, g95, gfortran).

gigabit network is STILL slow compared to memory access
across the internal bus.

I was once admining some machines at General Motors.
Both the filesystems with the app and the data were
on NFS mounts (user's home directory was on the
workstation).
Runtime for a CFD job was 8-10 hours.

Moving him to the same machine as the app was on cut
the execution time down to 2 1/2 hours.

To make a long story short, we eventually got him off
the SGI, and onto an HP (the CFD app wasn't available
for IRIX, only HP-UX)....and got all three things --
home dir, scratch-space filesystem, and app all on
the same machine cut the execution time down to
under 10 minutes.

60x speed increase!


There is no problem to compile some files which are stored locally on a nfs client.

See above.

However, when I try to compile some files stored on /home which is mounted through nfs, then it takes hours to make the link between all the .o files created.

Doesn't surprise me in the slightest.

Networks are SLOOOOOOOOOOOOWWWWWWWWWWWWWW
it's not the software...it's that you're trying to
push 32-bit quantities through a SERIAL connection,
but on the same machine, you're moving those 32-bit
quantities on a PARALLEL bus.


My server is an OpenSuSE 10.2 - 64bit machine and the nfs options are "root_squash,sync,insecure,rw".
All the clients run on OpenSuSE 10.2 - 32bit, with the options "rw,soft".

Except for the compilation, I do not face any other slow network communication.

It's worth checking the speeds. Do some dd transfers between local disks
and across the network for example.

Do you know if the problem is related to the "32bit clients - 64bit server" association?
Should I add another nfs option to the server or to the clients?

You probably want an rsize= and wsize= options. 8192 is the traditional
value but check the man pages for details

Cheers, Dave



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