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    SubjectRe: Process time measurement too optimistic
    On Wed, 8 Jul 1998, Pavel Machek wrote:

    > Linux currently charges processes for time at end of timeslice. That


    > means that if process wakes because of timer and finishes its
    > processing before end of jiffie, no time is charged to him.
    > It is possible to exploit this: I have code which eats ~50% of system
    > time, still, no time is charged to him. (This is partly dangerous
    > because scheduling strategy depends on same times.)

    The patch looks good, but I propose we try first what
    impact it will have on interactive and multimedia

    These tasks depend on the fact that their CPU time is
    being charged to background simulations...
    Besides, I wonder what would happen if your exploit is
    being run on an already loaded machine? It'll probably
    be charged for it's CPU time like all other processes.

    In short: a good patch, but we should test it
    thoroughly for it's impact on responsiveness.

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