[U-Boot] [PATCH 0/4] Network defrag

[Robin Getz]

On Sat 8 Aug 2009 05:50, Ben Warren pondered:
> Allesandro,
> 
> Alessandro Rubini wrote:
> > I finally fixed the defrag code, testing with NFS as well.
> > Didn't take performance figures, tough, for lack of time.

Checking out performance with tftp - server is Linux 2.6.27 located in 
Germany, client (U-Boot running net/next) is located in the USA. Packets 
fragmented, and arriving out of order.

U-Boot image (214268 bytes)

tftpblocksize      download          rate
 (bytes)             (ms)       (bytes/second)
   512              48,246         4,441
  1024              24,482         8,752
  1468 ( 1MTU)      17,243        12,426
  2048              12,517        17,118
  2948 ( 2MTU)       8,912        24,042
  4428 ( 3MTU)       6,167        34,744
  4096               6,608        32,425
  5908 ( 4MTU)       4,840        44,270
  7388 ( 5MTU)       4,042        53,010
  8192               3,641        58,848
  8868 ( 6MTU)       3,425        62,560
 10348 ( 7MTU)       2,974        72,047
 11828 ( 8MTU)       2,736        78,314
 13308 ( 9MTU)       2,508        85,433
 14788 (10MTU)       2,281        93,935
 16000               2,233        95,955
 16268 (11MTU)       2,174        98,559

So, that is 17-seconds (default - on the master), to 2 seconds. Wow - a 87% 
reduction!

Doing the same with a larger image (default kernel + ext2 file system == 
12Meg), gets similar results - goes from 928,688 ms / 12,493 bytes/second 
(yeah, that is 15 minutes with a tftpblocksize == 1468) to 107,626 ms / 
107,866 bytes/second (that is under two minutes with a tftpblocksize == 
16000)... Again - an 88% reduction in time spent waiting...

So - I think this is well worth the effort for those people who want to use 
tftp outside of a local network. (on a local network - things do not change 
that drastically - An 18Meg file with default tftpblocksize (1468 bytes) took 
5084ms to download, and with a tftpblocksize of 16268, it about half the 
time - 2625 ms...

Thanks to Alessandro for putting it together.

Feel free to add my Signed-off (once the docs have been updated explaining 
what this is all for).

-Robin