high-priority console

I have a process that occasionally runs away and never relinquishes the
processor. I’m trying to debug it, but I can’t lower the priority below
everything else on the system or it doesn’t work properly (and doesn’t
generate the bug). But since it is higher priority than everything else,
including devc-con, the only way to get the machine back is to reboot
which isn’t very helpful at all (and takes forever).

Is there a way to bring up a high-priority console on boot that would sit
idle until I needed to issue a slay command, or use pidin etc. to evaluate
the situation? I realize this observation may also change the behavior
(heisenbug) but it may give me more info, and at least I wouldn’t have to
reboot.

I usually have console 9 reserved for this purpose. Run a high-priority
shell there (and perhaps raise the priority of devc-con).

on -t /dev/con9 -p50 sh
slay -P55 devc-con

It is also possible to set up a ‘high priority telnet port’ for emergency
remote access.
Also it might be helpful to run spin on that high-priority console - then
you will see who’s actually eating up your cpu. I have seen a lot of cases
when it was not what I thought it should be… Sometimes it is not the cpu
utilization issue at all.

– igor

“Hans Fugal” <fugalh@byu.edu> wrote in message
news:pan.2004.04.10.05.22.45.533462@byu.edu

I have a process that occasionally runs away and never relinquishes the
processor. I’m trying to debug it, but I can’t lower the priority below
everything else on the system or it doesn’t work properly (and doesn’t
generate the bug). But since it is higher priority than everything else,
including devc-con, the only way to get the machine back is to reboot
which isn’t very helpful at all (and takes forever).

Is there a way to bring up a high-priority console on boot that would sit
idle until I needed to issue a slay command, or use pidin etc. to evaluate
the situation? I realize this observation may also change the behavior
(heisenbug) but it may give me more info, and at least I wouldn’t have to
reboot.