:> > It also has the unfortunate property of locking us into virtual
:> > wire mode, when in fact Microsoft demonstrated that wiring down
:> > interrupts to particular CPUs was good practice, in terms of
:> > assuring best performance.  Specifically, running in virtual
:> > wire mode means that all your CPUs get hit with the interrupt,
:> > whereas running with the interrupt bound to a particular CPU
:> > reduces the overall overhead.  Even what we have today, with
:> > the big giant lock and redirecting interrupts to "the CPU in
:> > the kernel" is better than that...
:> 
:> Terry, this is *total* garbage.
:> 
:> Just so you know, ok?
:
:What "this", exactly?
:
:That "virtual wire" mode is actually a bad idea for some
:applications -- specifically, high speed networking with
:multiple gigabit ethernet cards?

    All the cpu's don't get the interrupt, only one does.

:That Microsoft demonstrated that wiring down interrupts
:to a particular CPU was a good idea, and kicked both Linux'
:and FreeBSD's butt in the test at ZD Labs?

    Well, if you happen to have four NICs and four CPUs, and
    you are running them all full bore, I would say that
    wiring the NICs to the CPUs would be a good idea.  That
    seems like a rather specialized situation, though.

                                        -Matt

:That taking interrupts on a single directed CPU is better
:than taking an IPI on all your CPUs, and then sorting out
:who's going to handle the interrupt?
:...
:
:-- Terry




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