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SubjectMemory upgrade: not faster / nfs
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Date
Problem:
! NFS is a filesystem. Filesystems are not cached.
! The only thing that's cached in UN*X are block
! devices. This is the wrong place to cache.


My fastest CPU is a Pentium 100 on a diskless client.
I thought that I get only 5% cpu usage because I am
swapping over NFS. I bought another 32MB but the CPU
usage did not increase :-( The Ethernet LED is still
busy all the time.
I tracked the problem down to the following problem:

! NFS is a filesystem. Filesystems are not cached.
! The only thing that's cached in UN*X are block
! devices.

Because of this configuration the caching is done
in the server, not on the client =:-O
Transmitting data over the network is some magnitudes
slower than reading it from the buffers.
Compiling is a very I/O intensive task (all the
include files, the compiler, the .I .S .o files).
For this it doesn't matter how much memory I have on
my client. I can't get more than 5% CPU usage when
compiling.

Questions:
Is it correct how I see these things?
Why are filesystems not buffered?
Is there a nfs implementation that does buffering?


Christoph Trautwein email trautw@fzi.de
click <A HREF="http://www.fzi.de/sim/people/trautw/index.html">here </A>
FZI Forschungszentrum Informatik phone +49-721-9654-414
FZI,Haid-und-Neu-Str. 10-14, 76131 Karlsruhe, Germany fax +49-721-9654-474
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