Hello list,
There is something wrong in the PDP10 timer/clock handling. Take a look at this
job accounting data:
375 10:02:13 BATCH .KJOB/BATCH
376 10:02:13 USER
377 10:02:13 USER [LGNJSP Other jobs same PPN:14]
378 10:02:13 USER [LGNDTF Deleted 8 TMP file; 130 blocks freed]
379 10:02:13 USER Job 15 User JGUILLAUMES [200,200]
380 10:02:13 USER Logged-off TTY23 at 10:02:14 on 18-May-112
381 10:02:13 USER Runtime: 1:40:08, KCS:60085, Connect time:
0:00:53
382 10:02:13 USER Disk Reads:807, Writes:155, Blocks saved:3910
It's obvious than a runtime of 1:40:08 is not possible with a connect time of
0:00:53 ;). It seems that the CPU time calculation is wrong. It _could_ be a
TOPS-10 bug, but...
If I MONGEN a monitor specifying a (wrong) 50 Hz clock frequency then the real
time clock goes faster than normal (as expected), but the CPU time calculation
is not wrong. At least, it does NOT look wrong. The numbers you get are
coherent with the elapsed time:
115 11:10:37 BATCH .KJOB/BATCH
116 11:10:37 USER
117 11:10:37 USER [LGNJSP Other jobs same PPN:11]
118 11:10:37 USER Job 13 User JGUILLAUMES [200,200]
119 11:10:37 USER Logged-off TTY23 at 11:10:38 on 18-May-112
120 11:10:37 USER Runtime: 0:00:01, KCS:21, Connect time: 0:00:56
121 11:10:37 USER Disk Reads:1417, Writes:450, Blocks saved:4020
The CPU time problem is a little bit annoying. The default for the batch queues
is 5 minutes of CPU time, and if you specify the /TIME qualifier without a
value it goes up to one hour. That means most of jobs abort for exceeding their
time unless you specify something crazy like 24 hours. The problem manifests
when you try to do a GALGEN, which is based in a string of batch jobs: most of
them cancel because of this.
I've taken a look both into the timer C code for the simulator and the MACRO
source for the monitor. As obvious, I didn't understand a lot about MACRO-10
:), and on the other hand it could take some time for me to really understand
how the timer stuff works in SIMH. I could take a shot at it, if someone cares
to baby-sit me in the process ;) I see the 60 Hz value is a constant in
pdp10_tim.c, but I see that constant relates to other constants, and its
handling differs in the different CPU flavours, so I've not dared to change it
to 50 :) No idea about the consequences. I don't even know how the timer
communicates with the CPU, how does it generate its interrupts and all the
low-level stuff. Is there any low-level SIMH docs I could read? I don't have a
lot of free time, but I enjoy this stuff much more than the stupid IT
management work I do for a living ;)
Jordi Guillaumes i Pons
[email protected]
_______________________________________________
Simh mailing list
[email protected]
http://mailman.trailing-edge.com/mailman/listinfo/simh
