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    SubjectRe: Linux 2.6.0-test6
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    On Mon, Sep 29, 2003 at 12:55:12PM -0400, Ed Sweetman wrote:
    > Nick Piggin wrote:
    > >
    > >
    > >Rob Landley wrote:
    > >
    > >>On Sunday 28 September 2003 02:03, Con Kolivas wrote:
    > >>
    > >>>On Sun, 28 Sep 2003 11:27, Linus Torvalds wrote:
    > >>>
    > >>>>from Andrew Morton. Most notably perhaps Con's scheduler changes that
    > >>>>have been discussed extensively and made it into the -mm tree for
    > >>>>testing.
    > >>>>
    > >>>For those who are trying this for the first time, please note that the
    > >>>scheduler has been tuned to tell the difference between tasks of the
    > >>>_same_
    > >>>nice level. This means do NOT renice X or it will make audio skip unless
    > >>>you also renice your audio application by the same amount. Lots of
    > >>>distributions have done this for the old 2.4 scheduler which could not
    > >>>treat equal "nice" levels as differently as the new scheduler does
    > >>>and 2.6
    > >>>shouldn't need special treatment.
    > >>>
    > >>>So for testing note the following points:
    > >>>
    > >>>Make sure X is NOT reniced to -10 as many distributions are doing.
    > >>>Some shells spawn processes at nice +5 by default and this will make
    > >>>audio
    > >>>apps suffer.
    > >>>Make sure your hard disk, graphics card and audio card are performing at
    > >>>equal standard to your 2.4 kernel (ie dma is working, graphics is fully
    > >>>accelerated etc).
    > >>>
    > >>
    > >>I.E. with your new scheduler, priority levels actually have enough of
    > >>an effect now that things that aren't reniced can be noticeably
    > >>starved by things that are.
    > >>
    > >
    > >AFAIK, Con's scheduler doesn't change the nice implementation at all.
    > >Possibly some of his changes amplify its problems, or, more likely they
    > >remove most other scheduler problems leaving this one noticable.
    > >
    > >If X is running at -20, and xmms at +19, xmms is supposed to still get
    > >5% of the CPU. Should be enough to run fine. Unfortunately this is
    > >achieved by giving X very large timeslices, so xmms's scheduling latency
    > >becomes large. The interactivity bonuses don't help, either.
    > >
    >
    > there are 40 positions between -20 and 19, that doesn't equal 5% steps.
    > They don't even refer to % of cpu. If i nice a process to -20 it
    > doesn't get a given percentage of cpu just because it's -20. I may have
    > other processes at -20 as well. If you nice something to -20 and it is
    > actually using that cpu then things that are +19 shouldn't run and wont
    > run. If I nice -20 vmstat 1, it's not going to starve xmms (or any
    > better audio player). -20 means starve all and it should do that when
    > it actually makes use of the resources.
    >

    Why not run xmms with SCHED_RR or SCHED_FIFO?


    Regards.

    Pedro.

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