NFS 100:1 performance loss

Jakob Østergaard jakob at ostenfeld.dtu.dk
Fri Aug 18 16:32:50 EDT 2000


On Fri, 18 Aug 2000, Josip Loncaric wrote:

> Has anyone seen this NFS performance problem?
> 
> Our Beowulf has two servers w/RAID-0 arrays which deliver 45MB/s,
> connected via Gigabit Ethernet.  The machines are dual PIII/500 systems
> with 512MB of RAM each.  We are running Red Hat 6.2 updated to kernel
> 2.2.16-3 and recently we updated to nfs-utils-0.1.9.1-1.  We are running
> 16 kernel nfsd threads on each machine.  Here is how long it takes to
> copy a 28,955,860 byte file from machine 1 to machine 2:
> 
> rcp:       1.04 seconds (27.8 MB/s, where 1MB=10^6B)
> ftp:       1.12 seconds (25.8 MB/s)
> NFS 1KB:  12.35 seconds ( 2.3 MB/s, using rsize=wsize=1024)
> NFS 8KB: 129.42 seconds ( 0.2 MB/s, using rsize=wsize=8192)
> 
> Clearly, there is something very wrong with NFS, particularly with 8KB
> rsize/wsize (which should have improved performance!).  Our system
> manager tells me that reduced Linux NFS performance with 8KB rsize/wsize
> is a known problem, but even at 1KB our NFS is getting less than 10% of
> the rcp or ftp performance.
> 
> Any ideas?
> Josip

You do use the kernel nfs server right ?  knfsd, not the old
userspace nfs daemon...

Our NFS server gets us some 5 MB/s over 100MBit, which is
pretty good I think.  Linux NFS is not ``excellent'' yet, but
with the kernel NFS server it should be better than ``horrible''
at least    :)

Eventually, you could try the NFS patches (for both client and
server) available somewhere at sourceforge  (don't have the URL,
but a quick search should get you there).  They should resolve
most of the annying errors you see with Linux NFS, and they should
improve performance too I think.  We don't use them yet however,
so I don't have any experience to go with that one.

-- 
................................................................
: jakob at ostenfeld.dtu.dk  : And I see the elder races,         :
:.........................: putrid forms of man                :
:   Jakob Østergaard      : See him rise and claim the earth,  :
:        OZ9ABN           : his downfall is at hand.           :
:.........................:............{Konkhra}...............:

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