RFC 546

TENEX Load Averages for July 1973 🌸

Okay bestie, this is RFC 546 🎀 It's by B. Thomas from BBN-TENEX, with NIC number 17792, dated 10 August 1973. Heads up: the original doesn't give a category/status line or say it obsoletes or updates anything, so I'm not making that stuff up 🙈

This RFC shares utilization data for the BBN and ISI TENEX systems, and honestly the network community is gonna be so into it ✨

The graph on page 4 shows the load at the BBN-TENEX and USC-ISI Hosts during the work week for July 1973 💅 It plots the weekday hourly load average [1] for each site against time of day, and the time is Eastern Daylight Time 🕐

Reading data like this is lowkey tricky 😭 but I literally cannot stop myself from making these observations:

1. The BBN and ISI curves look basically the same 👯 and there's no skew between them. That suggests both user populations have similar working habits and live on the same time zone 🌍
2. Both curves line up super closely with "normal events" in the day of someone living on East Coast time ⏰ so the load at both sites is mostly driven by those users:

a. The load starts climbing between 7-8 a.m. EDT as users start their daily computing ☀️

b. It dips between 10-11 a.m. EDT (smoothed to a smaller rate of increase in the ISI curve) when users take their coffee break ☕

c. The load peaks sharply between 1-2 p.m. EDT as users come back from lunch and get back to computing 🍓

d. It goes down as the afternoon goes on and users head home from work 🚶‍♀️

e. It hits a local minimum between 6-7 p.m. EDT (not present in the ISI curve) when most people are eating dinner 🍝

f. It climbs to an evening peak between 9-10 p.m. EDT as some users come back from dinner and after-dinner stuff to keep computing 🌙

3. The ISI curve is smoother than the BBN one 🫶 The "coffee break" dip only shows up as a decrease in slope, and the dinner break and evening peak are completely smoothed out. This smoothing is probably due to the West Coast users of the ISI machine 🌴
4. During July, the BBN system was more heavily loaded than the ISI system 🔥 The data didn't include the number of active jobs, so there's no way to tell from it whether BBN had more users or just more demanding users 🤷‍♀️

The data on the graph is available as a side effect of the RSEXEC system 🧚 The server programs for RSEXEC (RSSER programs) regularly talk to each other and swap status information. The RSSER program at each site keeps a (dynamic) database of the info it collects from the RSSER programs at other sites. The NETLOAD command of the TENEX EXEC, along with many RSEXEC commands, uses that database 💜

The raw data for the BBN and ISI [2] load curves (and data for the other TENEX sites that run RSSER) was collected by a program. It creates daily load information files by periodically (every 3 minutes) reading load average data from the database maintained by RSSER 📂 The monthly summary was made by a program that analyzes those daily data files 📊

[The following graph is also available in .PS and .PDF format.]

    Weekday Hourly Load Averages
                              July 1973
       ^                                        B  BBN-TENEX
       |                                        I  ISI-TENEX
    10 +
       |
       |                            B
       |
       +
       |
       |
       |
       +                              B
Load   |
Avg.   |                                B
       |                            I
       +
       |
       |
       |                          *
       +                              I
       |
       |                      B         I B
       |                        B
     5 +
       |
       |                    B   I
       |                                  I
       +                      I
       |
       |
       |                  B
       +                                    I       B
       |                                    B
       |                                      I
       |                    I                   I B   B
       +                                          I
       |                  I                     B   I
       |                                      B
       |                B                             I B
       +  I             I                                 I
       |  B *                                             B
       |      * * I I *
       |          B B
    ---+--+-----------+-----------+-----------+-----------+>
       | 0-1 AM      6-7 AM     12-1 PM      6-7 PM      12
        (midnight)              (noon)            (midnight)
                 Time of Day (Eastern Daylight Time)

Endnotes 📝

[1] The TENEX load average is a measure of CPU demand 💻 It's the average number of runable processes over a given time period. For example, an hourly load average of 10 would mean that (for a single CPU system) at any time during that hour you could expect to see 1 process running and 9 others ready to run (i.e., not blocked for I/O) waiting for the CPU 🙈

[2] The BBN and ISI data was picked for this RFC because the BBN and ISI TENEXs are two of the major time-sharing service hosts on the network 🫶

[ This RFC was put into machine readable form for entry ] [ into the online RFC archives by Jim Larson 3/98 ] 💀