simh-3.9.0 is busy looping

Peter Jeremy peter at
Sun Oct 14 10:12:17 UTC 2012

On 2012-Oct-14 12:53:49 +0300, "Jukka A. Ukkonen" <jau at> wrote:
>It seems that simh-3.9.0 is busy looping and as a result also hogs one CPU
>to the max and prevents the system lowering the CPU clock frequency when
>there is actually nothing to do.

I haven't tried VAX but have used the PDP-11 simulator in simh for
quite a while.  On the PDP-11, simh originally used busy waits but
more recent versions can use blocking waits (at least in some
configurations).  I doubt that the issue is related to the FreeBSD
port and suggest you check the simh documentation and/or raise an
issue with simh.

Peter Jeremy
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