September 17, 1971
DATA TRANSFER RATES (RAND/UCLA)
The attached memo indicates data rates typical of our use of RJS at UCLA CCN. Earlier timing tests (similar but more detailed) with UCSB showed that most of the time was lost because of: (1) channel contention with our disk drive access; (2) our NCP runs at a higher priority than batch jobs but lower than text editing and interactive graphics; (3) OS interrupt handling is very slow on both ends; (4) spooling time of the remote system.
TO: John Heafner FROM: Bob Hoffman COPIES: Bob Mobley, Herb Shukiar
Here are some of the transmission rates I have noted over the network between Rand and UCLA. These were all taken at night when little else was happening on our 65.
SEND TO UCLA
# Cards Blocksize (bytes) Time (secs) Rate (bits/secs) 642 80 50 8218 375 80 30 8000 509 800 20 16288
RECEIVE FROM UCLA
For all figures below, the receiving file has blocksize of 1330 bytes, and each line is assumed to contain 100 bytes. This last assumption is fairly accurate, since most of the lines were from PL/I for which this is a very good number. Thus, for each rate, the number of bytes is the # Lines * 100.
# Lines Time (secs) Rate (bits/secs) 4900 200 19600 872 47 14843 3900 185 16865
As you can see from the send figures, blocking makes about a 2:1 difference. Memory also recalls a 2 or 3 to 1 advantage for blocking on receive when we were getting unblocked files from UCSB.
REH:gb [This RFC was put into machine readable form for entry] [into the online RFC archives by Kelly Tardif, Viagénie 10/99]