[16521] in Athena Bugs
NFS parameters in attach.conf
daemon@ATHENA.MIT.EDU (Thomas H. Grayson)
Wed Dec 2 17:36:38 1998
To: bugs@MIT.EDU
Cc: network@MIT.EDU, f_l@MIT.EDU, karen@MIT.EDU, jf@MIT.EDU, phils@MIT.EDU
Date: Wed, 02 Dec 1998 17:36:25 EST
From: "Thomas H. Grayson" <thg@MIT.EDU>
The default options for NFS mounts performed by 'attach' are
stored in the file /etc/athena/attach.conf. The standard Athena
attach.conf contains the following line:
options {nfs}:.* rsize=1024,wsize=1024,soft
The 'rsize' and 'wsize' parameters refer to the size in bytes of
the read and write buffers. These 1K buffer sizes are very
small. The Solaris man page for 'mount_nfs' indicates that the
defaults for both parameters are 8192 for NFS V2 and 32768 for
NFS V3. These low parameters have a significant negative impact
on NFS performance.
In an unscientific test, I set these values to 32768 by editing
attach.conf to contain the following revised line:
options {nfs}:.* rsize=32768,wsize=32768,soft
I then attached the 'arcinfo' NFS locker, and launched ArcView.
Since this executable is nearly 11 MB, it is a reasonable test of
NFS performance. On this modified workstation, ArcView launched
in about 42 seconds. On a similar workstation with the default
parameters, ArcView launched in about 99 seconds. Hence, with a
simple configuration change I decreased the program's launch time
by about 58%.
I strongly recommend that these parameters be increased for the
next Athena update. Launching ArcView over the network is
something we routinely require of our students in 11.520 and
11.521. The sluggish network performance hinders our hands-on
lab sessions considerably. We also use NFS for loading large GIS
data sets over the network. These, too, perform poorly,
especially on the Building 1 subnet (18.58).
Note that, contrary to the 'attach' man page, the '-o' or
'-mountoptions' switch cannot be used to set the rsize and wsize
options explictly. The 'attach' command silently ignores these
switches.
For the curious, my experiment was conducted in the Electronic
Classroom 1-115 using two of the Sun Ultra 10 workstations
located there. The room was not being heavily used at the time.
While I tested only on Suns, the same attach.conf parameters are
used on other platforms.
Tom Grayson
253-3535
