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    SubjectRe: [RFC PATCH v1 0/3] Scaled statistics using APERF/MPERF in x86
    Pavel Machek wrote:
    > Hi!
    >>> entitlement for the process as per the current CPU frequency. This
    >>> technique is used in powerpc architecture with the help of hardware
    >>> registers that accurately capture the entitlement.
    >> there are some issues with this unfortunately, and these make it
    >> a very complex thing to do.
    >> Just to mention a few:
    >> 1) What if the BIOS no longer allows us to go to the max frequency for
    >> a period (for example as a result of overheating); with the approach
    >> above, the admin would THINK he can go faster, but he cannot in reality,
    >> so there's misleading information (the system looks half busy, while in
    > Plus time one-second-computation-job returning anything else is just
    > wrong. Even when it only happens when overheated... or only on battery
    > power.
    > If you want scaled utime, you need new interface.

    We do have a new interface, two new parameters per-task utimescaled and
    stimescaled. They already exist in task_struct. Ditto for the delay accounting
    pieces. Did I misunderstand your need for a new interface? We still keep utime
    and stime around.

    Warm Regards,
    Balbir Singh
    Linux Technology Center

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      Last update: 2008-06-02 08:13    [W:0.023 / U:5.204 seconds]
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