Re: 4BSD/ULE numbers...

From: Taku YAMAMOTO (taku_at_tackymt.homeip.net)
Date: 09/30/05

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    Date: Fri, 30 Sep 2005 08:33:13 +0900
To: freebsd-current@freebsd.org

    Hi all,

    I found that slice_min and slice_max in sched_ule.c are calculated
    based on hz rather than stathz, which results to a thread hogging
    7.5 times more cpu time than the author's intension.

    For those who feel sluggish when doing computation-bound things,
    I recommend the following tunings with sysctl:

    # for RTC based systems...
    kern.sched.slice_min=1
    kern.sched.slice_max=18

    # for APIC based systems driven at hz=1000
    # (where stathz = hz * 2 / 15)
    kern.sched.slice_min=1 # (hz * 2 / 15) / 100
    kern.sched.slice_max=19 # (hz * 2 / 15) / 7

    The attached patch addresses this problem with the bonus of increased
    accuracy of tickincr.

    On Mon, 26 Sep 2005 13:47:38 -0400
    Kris Kennaway <kris@obsecurity.org> wrote:

    > On Mon, Sep 26, 2005 at 06:47:27PM +0200, Emanuel Strobl wrote:
    > > Hello,
    > >
    > > I tried ULE with BETA5 and for me it felt a bit sluggish when making ports.
    > > So I did some "realworld" simulation and compared 4BSD/ULE to see what
    > > numbers tell me. And the prooved my feeling right.
    > > It seems that ULE is priorizing nice a little higher, but in general the
    > > output of the 4 BSD machine is higher and finishing the tests took not so
    > > long as with ULE, especially the "make configure" differs horribly.
    >
    > That's consistent with my testing. ULE seems a bit more stable now in
    > 6.0 (except on my large SMP machines, which reboot spontaneously under
    > moderate load), but it doesn't perform as well as 4BSD under real
    > application workloads.
    >
    > Kris 

    -- 
-|-__   YAMAMOTO, Taku
 | __ <     <taku@tackymt.homeip.net>

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