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SubjectRe: /proc/sys/vm/freepages not writable.
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> > 1. The inactive_target is 1 second worth of allocations, minus
> > the amount of frees in 1 second, averaged over a minute
>
> So it cannot take load bursts. That's ok for a default, but for special loads
> it would be good if there was a way for the administrator to overwrite that,
> similar to the old freepages.

How about taking a decaying average (loadavg style) of the peak allocation-free
rate on a minute-by-minute basis. Then make the number of seconds at that
rate to use as the inactive_target a tunable parameter. That way, a user
could, if necessary, tune based on their expected type of load (length of
load bursts), and the alg. would tune to the load level (height of those
bursts). For a consistent load, peak rate ~= avg. rate, and this decays to
the current behavior, except that the "1 second of allocations" is tunable.

I haven't actually looked at the code, so I don't know how easy/hard this is to
implement, and while it does reintroduce a tuning parameter, it should be needed
less often, and has a much more user-meaningful value (burst length) than # of
free pages to keep handy, which depends on the code, and could change between
versions.

Evan
---
Fear is the mind killer. -- Frank Herbert, "Dune"
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