interrupt numbers

Matthew Dillon dillon at
Thu Apr 13 10:13:03 PDT 2006

:Terry Tree <terry.tree at xxxxxxxxx> wrote:
: > I take it everyone else is just as lost as me on how answer this one ?
:Answer what?  I didn't see any question in that message.  :-)
:(Apart from that, it doesn't seem to be related to DragonFly BSD.)
:Best regards
:   Oliver
:Oliver Fromme,  secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing

    I didn't see a question there either.  I did look at the web site,
    but while the graphs look quite interesting (though FreeBSD related,
    not DragonFly related), a vertical scale of 'ticks' rather than
    nanoseconds or microseconds doesn't really help one get any sense of

    In anycase, apart from the well understood overheads of issuing any
    sort of 'read' operation on an I/O device, I'm not sure how applicable
    any of that would be to a high performance system design since
    all the interrupts we care about (network, disk) are able to present
    multiple events per interrupt.

    I ran some interrupt overhead tests for a Bay Lisa talk a few months
    ago, which you can find here:

    That particular machine was operating in PIC mode (because Shuttle's
    BIOS's ACPI and MP interrupt tables are completely broken).  Interrupt
    overhead was approximately 1uS.  I am not particularly concerned
    over 1uS of interrupt overhead.

    It will become even less relevent as both Intel and AMD shift more of
    their production into multi-core cpus.

					Matthew Dillon 
					<dillon at xxxxxxxxxxxxx>

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