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SubjectRe: [PATCH] sched: Fix adverse effects of NFS client on interactive response
At 10:40 AM 1/8/2006 +1100, Peter Williams wrote:
>Mike Galbraith wrote:
>>> One slight variation of your scheme would be to measure the average
>>> length of the CPU runs that the task does (i.e. how long it runs
>>> without voluntarily relinquishing the CPU) and not allowing them to
>>> defer the shift to the expired array if this average run length is
>>> greater than some specified value. The length of this average for each
>>> task shouldn't change with system load. (This is more or less saying
>>> that it's ok for a task to stay on the active array provided it's
>>> unlikely to delay the switch between the active and expired arrays for
>>> very long.)
>>Average burn time would indeed probably be a better metric, but that
>>would require doing bookkeeping is the fast path.
>Most of the infrastructure is already there and the cost of doing the
>extra bits required to get this metric would be extremely small. The
>hardest bit would be deciding on the "limit" to be applied when deciding
>whether to let a supposed interactive task stay on the active array.

Yeah, I noticed run_time when I started implementing my first cut. (which
is of course buggy)

>By the way, it seems you have your own scheduler versions? If so are you
>interested in adding them to the collection in PlugSched?

No, I used to do a bunch of experimentation in fairness vs interactivity,
but they all ended up just trading one weakness for an other.


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