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SubjectRe: Load average and CPU hogs in realtime scheduling
On Sun, Nov 16, 1997 at 01:26:32PM +0100, Olaf Titz wrote:
> MAME (arcade machine emulator) is cool. :-) In order to let it run
> smoothly, I run it in SCHED_FIFO (or was ist _RR?) mode (the svgalib
> version). This program seems to take 100% of the CPU time and no other
> process on the machine gets to run, not surprisingly.
>
> What does surprise me, however: when I exit MAME and let my machine
> resume normal operation, it displays a load average of perhaps 15 or
> 20, depending on how long MAME ran, despite no processes in R or D
> state. The load drops quickly to the usual "0+noise".
>
> Looks like there is something slightly wrong with load average
> computation.

Nope, the load average calculation is actually ok. The load is so high
because during the time the SCHED_FIFO process sucks all the CPU the
scheduler will never select one of the other processes waiting to run.
So when MAME quits all those processes get run, finish their jobs and
the load average goes back down to what you expect it to be.

Ralf

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