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    SubjectRe: [patch 2/4] Expose Power Management Policy option to users
    Kristen Carlson Accardi wrote:
    > I think what you are saying is that you'd like a way to use your HIPM
    > and DIPM without ALPM on the AHCI driver. Fine - it's really easy
    > to add these levels later - if they don't make sense at the sysfs interface
    > we can add module params to specify the definition of "min_power" as
    > being performed via HIPM and DIPM instead of ALPM - although as of yet we
    > have no evidence what so ever that this method actually adds value over
    > ALPM.

    I don't really care whose PS implementation goes in. Believe me. I try
    to stay away from that. I don't even like my previous implementation.

    ALPM has unnecessary performance penalty && is not applicable to
    non-ahci controller. Have you tested ALPM on non-intel ahcis? There
    are a lot out there these days.

    I don't think the interface you're suggesting is a good one. Do you?

    >> Also, I generally don't think AHCI ALPM is a good idea. It doesn't have
    >> 'cool down' period before entering PS state which unnecessarily hampers
    >> performance and might increase chance of device malfunction.
    >
    > "might increase"? How about some actual examples of where you've shown
    > this to be a problem?

    I wouldn't have used "might" if I had actual examples. Well, feel free
    to disregard anything following the "might". I just feel uneasy about
    jumping back and forth between PS and active states between consecutive
    commands.

    > I can assert that I think ALPM is a good idea,
    > because I've never had a report of it causing problems. Windows has
    > been using this feature for a very long time - and you have to admit that
    > they have a pretty large market share. Nobody is complaining about ALPM
    > increasing device malfunction, so unless you have proof it seems insane
    > to nak due to this.

    Is ALPM enabled by default? How do they deal with the performance
    degradation?

    --
    tejun
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