[Simh] Excessive paging of the real machine running SIMH - VAX

[Nelson H. F. Beebe]

Villy Madsen <Villy.Madsen at shaw.ca> asks today about excessive
paging on the SIMH VAX running with a 128MB memory limit on top of
Windows XP with 1GB physical memory.

I'm running two SIMH VAXes on a single-CPU GNU/Linux 3GHz Pentium 4
with hyperthreading turned on, which makes the O/S believe that there
are two CPUs.  For each of them, I have "set cpu 256M" in the startup
.cfg file, but they aren't using all of that memory while running.
Here is what the top utility currently shows:

  PID USERNAME PRI NICE  SIZE   RES STATE   TIME   WCPU    CPU COMMAND
13284 root      16    0  165M   52M sleep  50.9H 88.47% 95.87% lt-hercules
 7795 root      35   10  260M   54M run   468.7H 22.72%  5.33% vax
 7824 root      35   10   68M   61M run   467.0H 22.63%  3.80% vax

Notice that the Hercules simulator with Debian GNU/Linux for IBM S/390
is also running, but they each only need about 50MB--60MB of RAM most
of the time.

I see no swap activity at all:

# top
last pid: 18014;  load avg:  3.00,  3.01,  3.00;  up 24+19:31:33    11:51:33
92 processes:  3 running, 89 sleeping
CPU states:  0.0% user, 51.6% nice,  0.3% system, 48.1% idle,  0.0% iowait
Memory: 700M used, 310M free, 185M buffers, 101M cached
Swap: 198M used, 1802M free, 67M cached
...

# vmstat -a
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
 r  b   swpd   free  inact active   si   so    bi    bo   in    cs us sy id wa
 3  0 202604 317400 179320 310080    0    0     3     9    6     8 86  0 13  0

It may be that increasing Villy's VAX CPU memory size from 128M to
256M might eliminate the excessive swapping that he sees on startup
and shutdown.

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- Nelson H. F. Beebe                    Tel: +1 801 581 5254                  -
- University of Utah                    FAX: +1 801 581 4148                  -
- Department of Mathematics, 110 LCB    Internet e-mail: beebe at math.utah.edu  -
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