[Simh] Workaround for idle

[Thomas Pfau]

I have two machines at home that I run the simh VAX simulator on.  One is
an AMD64.  The other is my Celeron laptop.

Both have the ability to alter the CPU clock speed to reduce power
consumption and heat.  The Celeron is much more aggressive than the AMD. 
It can be scaled back from 2.2GHz to 275KHz although I don't let it go
below 550KHz.  The AMD64 will scale back from 2.4GHz to 1GHz.

The Celeron is the machine that gives me the bigger problem with idle
detection.  That was the machine with the 20 minute bootstrap.

I have a feeling that the host processor speed scaling is probably having
an effect on simh idle detection.  Is that possible?

I'll try the suggestion below when I get home tonight to see if the
Celeron will boot faster.

bsupnik at comcast.net wrote:
> The idle detector in the VAX is declaring idle when it shouldn't.  In
> addition, device timeouts are causing idles when they shouldn't.
>
> You can work around the problem, FOR VMS ONLY, by changing the parameters
> of the idle detector, as follows:
>
> sim> d idle_ipl 8
> sim> d idle_wait 1000
>
> [On a really fast CPU, idle_wait may need to be higher.]
>
> The idle detector was tripping on legitimate activity at IPL's 0 and 2,
> causing the system to go idle when it really wasn't.
>
> In 3.7-2, the SET CPU IDLE command will take an OS parameter to specify
> how to tune the idle detector.
>
> /Bob
> _______________________________________________
> Simh mailing list
> Simh at trailing-edge.com
> http://mailman.trailing-edge.com/mailman/listinfo/simh
>


-- 
tom_p
http://nbpfaus.net/