[Simh] Reduce CPU usage

[Mark Pizzolato - Info Comm]

True, but the current idling logic in the VAX simulators should detect and be well behaved under all available versions of VMS as well as when sitting idle at the console boot rom prompt (>>>).

Sergey suggest that the problem may be related to too large a host OS clock tick.  This turns out not to be the case either.

Priya sent me the following SHOW VERSION output:

MicroVAX 3900 simulator V4.0-0 Beta
        Simulator Framework Capabilities:
                64b data
                64b addresses
                Ethernet support
                Idle/Throttling support is available
                Virtual Hard Disk (VHD) support
                RAW disk and CD/DVD ROM support
                Asynchronous I/O support
        Host Platform:
                Compiler: GCC 4.7.2 20121109 (Red Hat 4.7.2-8)
                Simulator Compiled: Nov  5 2013 at 15:19:27
                Memory Access: Little Endian
                Memory Pointer Size: 32 bits
                Large File (>2GB) support
                OS clock tick size: 2ms
                OS: Linux localhost.localdomain 3.6.10-4.fc18.i686.PAE #1 SMP Tue Dec 11 18:15:08 UTC 2012 i686 i686 i386 GNU/Linux

        git commit id: 32b8f063


The OS clock tick size of 2 is the same as on my FC18 test system.

I also received a copy of the config file that is being used.

I responded with the following:

Your vax.ini file doesn't have a "SET CPU IDLE" command.  Once that command has been issued, idle detection may take up to 20 seconds before the running simulator's clock calibration will allow idling.  Normally this 20 seconds would happen during the boot of the simulated system and not be noticed.  Clearly idling will ONLY be noticed on the host system when the guest system is actually idling.  What operating system (and version) is running on the guest?  How do you know the guest system is actually idle?

We'll see what comes back....


-          Mark

From: Hittner, David T (IS) [mailto:david.hittner at ngc.com]
Sent: Friday, January 24, 2014 12:43 PM
To: Mark Pizzolato - Info Comm; Priya Chincholikar; simh at trailing-edge.com
Subject: RE: [Simh] Reduce CPU usage

And what version of VMS are you running? Different versions of VMS have different idle characteristics..

Dave

From: simh-bounces at trailing-edge.com<mailto:simh-bounces at trailing-edge.com> [mailto:simh-bounces at trailing-edge.com] On Behalf Of Mark Pizzolato - Info Comm
Sent: Friday, January 24, 2014 8:26 AM
To: Priya Chincholikar; simh at trailing-edge.com<mailto:simh at trailing-edge.com>
Subject: EXT :Re: [Simh] Reduce CPU usage

Hi Priya,

This is one of those "it works for me" cases.  Idling works fine for a VMS guest on my fc18 x86 test system.

What is the output of "SHOW VERSION" done at the "sim>" prompt?
What does your configuration file look like?


-          Mark

From: simh-bounces at trailing-edge.com<mailto:simh-bounces at trailing-edge.com> [mailto:simh-bounces at trailing-edge.com] On Behalf Of Priya Chincholikar
Sent: Friday, January 24, 2014 3:40 AM
To: simh at trailing-edge.com<mailto:simh at trailing-edge.com>
Subject: [Simh] Reduce CPU usage

Hi,

The cpu usage while running the emulator is shown as 97% to 99%. Is there a way to reduce this?
And I tried setting the cpu idle but no use. CPU utilization is still high.

sim> show cpu
CPU     idle disabled, model=VAXServer 3900 (KA655), NOAUTOBOOT
        64MB, HALT to console
sim> SET CPU IDLE=VMS
sim> show cpu
CPU     idle=VMS, idle enabled, model=VAXServer 3900 (KA655), NOAUTOBOOT
        64MB, HALT to console

Host OS used is Linux. fc18.

Thanks,
Priya


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