Time slicing -- How does 4.3bsd do it?

[John F. Haugh II]

In article <15504 at mimsy.UUCP> chris at mimsy.UUCP (Chris Torek) writes:
>Thus, if by `quantum' you mean the typical scheduler quantum, the value
>is essentially random, depending on when the process was scheduled with
>respect to the constant 100 ms ticks.

In the UNIX idiom the answer would be 100ms.  Every 100ms you get a
chance to lose the CPU, but not more often [ baring a process being
awoken on a higher priority ].  Older kernels used a 1 second quantum.
I suspect this is what prompted the question.

>                                       In the absence of clock-related
>voluntary context switching, the unfairness should average out to the
>point where it can be ignored, but that absence is not guaranteed.

All scheduling is unfair.  Doesn't the joke go "If this is timesharing
I want my share now."?
-- 
John F. Haugh II                        +-Quote of the Week:-------------------
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