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Aucbvax.3165 fa.unix-wizards utzoo!decvax!ucbvax!unix-wizards Tue Sep 15 19:27:54 1981 Re: 11/70 Loads >From mike.bmd70@BRL Tue Sep 15 19:21:50 1981 Lt. Breitling - We are running an enhanced V6 UNIX on 2 11/70s here, and have some of the following performance observations:

1) The NCP code does not seem to use much of the CPU, cycle wise. The user programs are not really much worse. You do pay a penalty in core usage, because the network software does occupy a fair amount of core... 3 TELNETs, the NCP, ServerTelnetDaemon, FTPServerDaemon, and an active FTP or two takes almost 600 Kb. (This observation made with memory lights & memory utilization analyzer). This does not grow linearly with load, however, thanks to the "pure text" mechanism.

2) Our primary 11/70 delivers sub-second (0.1 -> 0.2 s) response time for most requests (editor commands, WHO, MOUNT, etc) which do not demand significant I/O from the moving head disks. We can deliver this with 30 users on the system (1/3 doing program development, 2/3 editing and TROFF). However, we have a rather special hardware configuration which aids this: ROOT 4096 blocks of BULK CORE (RF-11 interface) SWAP 4872 blocks of RK-11 /tmp 4096 blocks of BULK MOS * 3 CDC 80 Mb drives, Massbus interface -MEMORY- 1.5 Mb

3) "Number cruncher" processes tend to get little or no CPU time durring prime time; they just sit around and wait for spare cycles. This is due to our "High Performance Scheduler". Gives great interactive response, and prevents "batch" work from interfering with interactive terminals.

4) Although 1.5 Mb of main memory does seem to be sufficient now, when we had only 0.5 Mb, we did observe swapping rates of up to 10/sec before performance began to suffer too much. Swapping is to be avoided.

5) With the addition of another MASSBUS disk interface and more drives, we could probably support 48-55 users with the same performance, although the CPU would probably start to run out of steam at this point.

6) I could go on and on about performance issues. If there is interest, we could put together a somewhat longer letter.... What interests people?

7) We plan to put UNIX on the HEP (Heterogeneous Element Processor), a multi-CPU machine, where the raw speed of each CPU element is 10 MIPS and only costs $250K - $500K (not sure). Our initial configuration will be 40 MIPS. (From the people who brought you ENIAC, ...HEP!) We think it will make a superb interactive facility.

Cheers, -Mike

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