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    SubjectRe: [RFC][PATCH] iowait statistics
    Date
    On 14 May 2002 00:18, Andrew Morton wrote:
    > Rik van Riel wrote:
    > > 4) on SMP systems the iowait time can be overestimated, no big
    > > deal IMHO but cheap suggestions for improvement are welcome
    >
    > I suspect that a number of these statistical accounting mechanisms
    > are going to break. The new irq-affinity code works awfully well.
    >
    > The kernel profiler in 2.5 doesn't work very well at present.
    > When investigating this, I ran a busy-wait process. It attached
    > itself to CPU #3 and that CPU received precisely zero interrupts
    > across a five minute period. So the profiler cunningly avoids profiling
    > busy CPUs, which is rather counter-productive. Fortunate that oprofile
    > uses NMI.

    What, even local APIC interrupts did not happen on CPU#3
    in these five mins?
    --
    vda
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