bad NFS/UDP performance

[Danny Braniss]

> > it more difficult than I expected.
> > for one, the kernel date was missleading, the actual source update is the key, so
> > the window of changes is now 28/July to 19/August. I have the diffs, but nothing
> > yet seems relevant.
> >
> > on the other hand, I tried NFS/TCP, and there things seem ok, ie the 'good' and the 'bad'
> > give the same throughput, which seem to point to UDP changes ...
> 
> Can you post the network-numbers?
so I ran some more test, these are for writes IO:

server is a NetApp:

kernel from 18/08/08 00:00:0 : 
                    /----- UDP ----//---- TCP -------/
       1*512  38528 0.19s   83.50MB 0.20s   80.82MB/s
       2*512  19264 0.21s   76.83MB 0.21s   77.57MB/s
       4*512   9632 0.19s   85.51MB 0.22s   73.13MB/s
       8*512   4816 0.19s   83.76MB 0.21s   75.84MB/s
      16*512   2408 0.19s   83.99MB 0.21s   77.18MB/s
      32*512   1204 0.19s   84.45MB 0.22s   71.79MB/s
      64*512    602 0.20s   79.98MB 0.20s   78.44MB/s
     128*512    301 0.18s   86.51MB 0.22s   71.53MB/s
     256*512    150 0.19s   82.83MB 0.20s   78.86MB/s
     512*512     75 0.19s   82.77MB 0.21s   76.39MB/s
    1024*512     37 0.19s   85.62MB 0.21s   76.64MB/s
    2048*512     18 0.21s   77.72MB 0.20s   80.30MB/s
    4096*512      9 0.26s   61.06MB 0.30s   53.79MB/s
    8192*512      4 0.83s   19.20MB 0.41s   39.12MB/s
   16384*512      2 0.84s   19.01MB 0.41s   39.03MB/s
   32768*512      1 0.82s   19.59MB 0.39s   40.89MB/s

kernel from 19/08/08 00:00:00:
       1*512  38528 0.45s   35.59MB 0.20s   81.43MB/s
       2*512  19264 0.45s   35.56MB 0.20s   79.24MB/s
       4*512   9632 0.49s   32.66MB 0.22s   73.72MB/s
       8*512   4816 0.47s   34.06MB 0.21s   75.52MB/s
      16*512   2408 0.53s   30.16MB 0.22s   72.58MB/s
      32*512   1204 0.31s   51.68MB 0.40s   40.14MB/s
      64*512    602 0.43s   37.23MB 0.25s   63.57MB/s
     128*512    301 0.51s   31.39MB 0.26s   62.70MB/s
     256*512    150 0.47s   34.02MB 0.23s   69.06MB/s
     512*512     75 0.47s   34.01MB 0.23s   70.52MB/s
    1024*512     37 0.53s   30.12MB 0.22s   73.01MB/s
    2048*512     18 0.55s   29.07MB 0.23s   70.64MB/s
    4096*512      9 0.46s   34.69MB 0.21s   75.92MB/s
    8192*512      4 0.81s   19.66MB 0.43s   36.89MB/s
   16384*512      2 0.80s   19.99MB 0.40s   40.29MB/s
   32768*512      1 1.11s   14.41MB 0.38s   42.56MB/s