Re: [PATCH v6 00/12] *** A Method for evaluating dirty page rate ***

[David Edmondson <dme@dme.org>]

Trying to think like a control plane developer and user (of which I am
neither) raised some questions about the overall interface provided
here. If everyone else is happy with the current interface, then I'll
shut up :-)

It seems like it should be possible to query the last measured dirty
rate at any time. In particular, it should be possible to query the
value before any rate has been measured (either returning an error, or
if that is unpalatable perhaps a result with a zero interval to indicate
"this data isn't useful"), but also *during* a subsequent measurement
period.

That is, the result of the previous measurement should always be
available on demand and a measurement becomes "current" when it
completes.

Given that we allow the caller to specify the measurement interval, some
callers might specify a long period. As only one measurement can be
taken at a time, a long running measurement rules out taking a short
measurement. That's probably okay, but does lead me to wonder whether
the API should include a mechanism allowing the cancellation of an
in-progress measurement.

dme.
-- 
I can't explain, you would not understand. This is not how I am.