[Simh] idle and throttle on Solaris

[Michael L. Umbricht]

Mark, I downloaded the beta copy and ran it before modifying /etc/system

MicroVAX 3900 simulator V4.0-0 Beta        git commit id: 2c0cedcc
sim> set idle
Idling is not available, Minimum OS sleep time is 11ms
Command not allowed

I then added just one line to the end of /etc/system

set hires_tick=1

followed by a Solaris reboot.

Setting idle or throttle then worked and the cpu usage on a SunFire V100
550 MHz Ultra drops to a reasonable value of 5-10% or so. (Slightly on
the higher side of that range for vax780 as compared to microvax3900.)

According to the
https://blogs.oracle.com/jtc/entry/overhead_in_increasing_the_solaris
link from Sergey the "set hires_hz=1000" line is redundant as the
default is already 1000 per second. 

The interrupts did increase by a factor of 4 or 5 as expected but so far
I do not see any adverse impact on system performance. The average SY
time on an idle system barely increased from 1 to 2%

Thanks for the help.

-mikeu

> -------- Original Message --------
> Subject: RE: [Simh] idle and throttle on Solaris
> From: Mark Pizzolato - Info Comm <Mark at infocomm.com>
> Date: Mon, May 19, 2014 11:21 am
> To: "Michael L. Umbricht" <mike at umbricht.org>, "simh at trailing-edge.com"
> <simh at trailing-edge.com>
> 
> 
> On Monday, May 19, 2014 at 7:06 AM, Michael Umbricht wrote:
> > I am running vms on vax and vax780 in simh V3.9-0 on a Solaris Ultra.
> > The SET CPU IDLE and SET THROTTLE commands return "Command not
> > allowed"
> > and the sim consumes all available cpu cycles on the host. I found some
> > information about a similar issue on NetBSD hosts:
> > 
> > https://github.com/simh/simh/issues/1
> > 
> > Is there a way to modify Solaris to allow idle detection to work as suggested
> > in the post above?
> > 
> > uname -a: SunOS rcs 5.10 Generic_147147-26 sun4u sparc SUNW,UltraAX-i2
> 
> This subject was explored about 14 months ago on the HECnet mailing list.
> 
> Info we found at the time suggested that you could change or add the following to /etc/system file:
> 
> set hires_tick=1
> set hires_hz=1000
> 
> I don't know if this will work for your OS version.  Let us know.
> 
> The above suggestion was made back in March 2013, but I don't see that confirmation that the change actually worked never made it back to the list, so please let us know.
> 
> Meanwhile, if you use the latest code from github: https://github.com/simh/simh/archive/master.zip you will be told what simh believes the OS tick size is if it rejects your effort to enable idling.  Clearly this is only one of many other more significant enhancements.
> 
> Thanks.
> 
> - Mark