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    SubjectRe: [PATCH] remove interactive credit
    Nick Piggin wrote:
    > Con Kolivas wrote:
    >
    >> remove interactive credit
    >>
    >>
    >>
    >> ------------------------------------------------------------------------
    >>
    >> Special casing tasks by interactive credit was helpful for preventing
    >> fully
    >> cpu bound tasks from easily rising to interactive status.
    >> However it did not select out tasks that had periods of being fully
    >> cpu bound
    >> and then sleeping while waiting on pipes, signals etc. This led to a more
    >> disproportionate share of cpu time.
    >>
    >> Backing this out will no longer special case only fully cpu bound
    >> tasks, and
    >> prevents the variable behaviour that occurs at startup before tasks
    >> declare
    >> themseleves interactive or not, and speeds up application startup
    >> slightly
    >> under certain circumstances. It does cost in interactivity slightly as
    >> load
    >> rises but it is worth it for the fairness gains.
    >>
    >> Signed-off-by: Con Kolivas <kernel@kolivas.org>
    >>
    >
    > I'm scared :(
    >
    > I'm in favour of any attempts to simplify things... but will it be two
    > months or three before this spontaneously explodes for half our userbase?
    >
    > Andrew's boss so he gets to decide >:)

    If I read the intent right, this is an example of worst case avoidance,
    where a little average interactivity is traded for preventing the case
    where a single misguided process gets most/all of the CPU and
    performance falls off the edge of the table. As a user I see that as the
    same line of thought which gave us low-latency patches, to trade a
    miniscule bit of one thing to avoid something really undesirable.

    I suspect there will be people who don't want to make this trade,
    although it sounds like a good one to me.

    --
    -bill davidsen (davidsen@tmr.com)
    "The secret to procrastination is to put things off until the
    last possible moment - but no longer" -me
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