Messages in this thread | | | Date | Wed, 30 Jul 2003 17:08:34 +0100 | From | John Bradford <> | Subject | Re: PATCH : LEDs - possibly the most pointless kernel subsystem ever |
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> > Does anybody have any suggestions for recommended standard uses for > > parallel port connected LEDs?
> At one point I had 12 LEDs on parport. LEDs were fast enough to be > drive at interrupt entry/exit. > They were: > Yellow not idle task > Green interrupt > " bh > " pagefault > Red lowest 4 bits of PID > Red, low intensity serial i/o > " network i/o > > It actually looked very good. Glow of interrupt led told you > interrupt load, pid LEDs told you about what kind of load it is > experiencing (you could tell shell script from make and from > computation, and if machine hard-died, you at least knew if it was > interrupt or process context).
Sounds like exactly what we need. If we standardise on something like the above, we could just have a CONFIG_FRONT_PANEL_MONITOR and ask people to send in the LED status with bug reports.
> But this kind of blinkenlights needed pretty fast LEDs. (At 486 time > I decided that parport on ISA is fast enough..)
I'll buy some LEDs and build a parallel port connected LED panel tomorrow... Do you think the overhead of driving the LEDs would have too much of a negative effect on system performance? If so, or if we want more flexibility, maybe we could work out a design for a PCI card, which could include more than 12 LEDs - 7-segment numeric displays of pid, etc.
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