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    SubjectRe: Decreasing stime running confuses top (was: top displaying 9999% CPU usage)
    Il Thu, Oct 04, 2007 at 01:32:44AM +0200, Frans Pop ha scritto: 
    > On Wednesday 03 October 2007, you wrote:
    > > On Wed, Oct 03, 2007 at 09:27:41PM +0200, Frans Pop wrote:
    > > > On Wednesday 03 October 2007, you wrote:
    > > > > On Wed, 3 Oct 2007, Ilpo Järvinen wrote:
    > > > > > On Wed, 3 Oct 2007, Frans Pop wrote:
    > > > > > > The only change is in 2 consecutive columns: "2911 502" -> "2912
    > > > > > > 500". Is processor usage calculated from those? Can someone
    > > > > > > explain how?
    > > > > >
    > > > > > The latter seems to be utime ...decreasing. No wonder if
    > > > > > arithmetics will give strange results (probably top is using
    > > > > > unsigned delta?)...
    > > > >
    > > > > Hmm, minor miscounting from my side, stime seems more appropriate...
    > > >
    > > > So, is it normal that stime decreases sometimes or a kernel bug?
    > > > /me expects the last...
    > >
    > > Let me guess... Dual core AMD64 ?
    >
    > Nope: Intel(R) Pentium(R) D CPU 3.20GHz

    I just notice the same thing here, with a Core2 Duo (which is supposed
    to have synced TSCs) and working HPET.

    > The following may well be relevant.
    > With 2.6.22 and early 2.6.23-rc kernels (rc3-rc6) I often had this in my
    > kernel log (see http://lkml.org/lkml/2007/9/16/45):
    > checking TSC synchronization [CPU#0 -> CPU#1]:
    > Measured 248 cycles TSC warp between CPUs, turning off TSC clock.
    > Marking TSC unstable due to check_tsc_sync_source failed

    I don't see this though, TSCs are always syncronized between the 2
    cores.

    Luca
    --
    Ligabue canta: "Tutti vogliono viaggiare in primaaaa..."
    Io ci ho provato e dopo un chilometro ho fuso il motore e bruciato
    la frizione...
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