Description of Problem:


(from my post to comp.os.linux.redhat):





        The short version: why has NFS client support gotten so much worse


between RH 7.2 and 7.3, and what can we do about it?





        Alright, some background: we're a mixed-platform Unix shop, with


Solaris Sparc servers and a mix of primarily Linux and Solaris desktops


(with a few of just about everything else for good measure - IRIX, Tru64,


HP-UX, AIX, OS X, Win2k).  The network is NFS/NIS using the automounter,


and has worked quite well historically.





        While most of our Linux boxes are running RedHat 7.2, I've begun


installing a few limited RH 7.3 test boxes in the group for testing


purposes.  So far, it's going great except for one thing: the NFS


performance.  If the systems attempt to copy any large files or perform


any non-trivial NFS task, they get errors of the sort of:





        "nfs: task xxxx can't get a request slot"





        ...and the task doesn't really complete.  Even when it does work,


performance is terrible - copying a 256M file to local disk takes minutes


instead of seconds on similar machines (10:35.43 on a RH 7.3 box, compared


to 0:50.18 on 7.2).





        I have tried patching the 7.3 boxes to the most recent kernel


RPM (2.4.18-5), which hasn't changed anything significantly.  On searching


Usenet, I've found word that I should be lowering the default wsize and


rsize to 8k or 16k; I don't consider this an acceptable alternative, given


that we use the automounter and any changes I make there will affect all


other systems on our network.





        Otherwise, I'm stumped.  And I'm really tempted to give RH 7.3 a


miss, which seems a shame but apparently necessary.








Version-Release number of selected component (if applicable): 


7.3, kernels 2.4.18-3 and 2.4.18-5 (either)





How Reproducible:


Perfectly








Steps to Reproduce:





On two (similar but not identical) systems:





# mount reno:/export/reno/ext36 /mnt


# time cp /mnt/isoimages/valhalla-i386-disc1.iso /scratch





RH 7.2 (2.4.9-34) results:


0.060u 16.580s 2:15.84 12.2%    0+0k 0+0io 103pf+0w





RH 7.3 (2.4.18-5) results: 


0.070u 62.730s 5:47.73 18.0%    0+0k 0+0io 100pf+0w