Data transfer rates (Rand/UCLA)
Measured file transfer rates between Rand and UCLA in 1971, and the reasons they were slow.
Heafner, J.F. and E. Harslem, "Data transfer rates (Rand/UCLA)", RFC 227, DOI 10.17487/RFC0227, September 1971, <https://www.rfc-editor.org/info/rfc227>.
@misc{rfc227,
series = {Request for Comments},
number = 227,
howpublished = {RFC 227},
publisher = {RFC Editor},
doi = {10.17487/RFC0227},
url = {https://www.rfc-editor.org/info/rfc227},
author = {J.F. Heafner and E. Harslem},
title = {{Data transfer rates (Rand/UCLA)}},
pagetotal = 2,
year = 1971,
month = sep,
} RFC text
Network Working Group J. Heafner Request for Comments: 227 E. Harslem NIC: 7631 September 17, 1971 Updates: RFC 113 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. MEMORANDUM 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, Viag�nie 10/99]
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§1Why Transfers Were Slow
The attached memo shows data rates typical of Rand's use of RJS at UCLA CCN. Earlier, more detailed timing tests with UCSB showed most time was lost because of four things: channel contention with their disk drive access; their NCP running at higher priority than batch jobs but lower than text editing and interactive graphics; very slow OS interrupt handling on both ends; and spooling time on the remote system.
Busy disks, a busy computer and slow handling of interruptions all slowed the files down.
§2The Measurements
The memo was taken at night when little else was happening on their 65. Sending to UCLA, 642 cards of 80 bytes took 50 seconds (8218 bits per second), 375 cards of 80 bytes took 30 seconds (8000) and 509 cards at a block size of 800 bytes took 20 seconds (16288).
Receiving from UCLA, the file had a blocksize of 1330 bytes and each line was assumed to be 100 bytes. 4900 lines took 200 seconds (19600), 872 lines took 47 seconds (14843) and 3900 lines took 185 seconds (16865).
They sent and received piles of cards and lines and timed each one.
| Cards | Blocksize (bytes) | Time (secs) | Rate (bits/secs) |
|---|---|---|---|
| 642 | 80 | 50 | 8218 |
| 375 | 80 | 30 | 8000 |
| 509 THIS RFC | 800 | 20 | 16288 |
§3Blocking Helps
The memo concludes from the send figures that blocking makes about a 2:1 difference. Memory also recalls a 2 or 3 to 1 advantage for blocking on receive when unblocked files were coming from UCSB. The RFC updates RFC 113.
Sending files in bigger bundles roughly doubled the speed.