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SubjectRe: graphical swap comparison of aa and rik vm
Date
On Thursday 01 November 2001 01:23, Mark Hahn wrote:
> > Here is the graph http://safemode.homeip.net/vm_swapcomparison.png .
> > It's
>
> here's my munge of the same data:
> http://mhahn.mcmaster.ca/~hahn/foo.png
> the measures I find interesting are the SI/SO rates. first, the most
> obvious feature is that Rik-VM has a serious problem knowing when to *stop*
> swapping out. but SO isn't a bad thing unless it's obsessive: it's when
> you see high *swap-in* that you know the VM has previously chosen bad pages
> to SO. and this is the second big difference: Rik-VM doesn't make nearly as
> many mistakes - especially look at Andrea-VM thrashing out-in-out at ~
> samples 26-32.
>
> also, if you merely sum the SI and SO columns for each:
> sum(SI) sum(SO) sum(SI+SO)
> Rik-VM 43564 317448 290032
> AA-VM 118284 171748 361012
> to me, this looks like the same point: Rik being SO-happy,
> Andrea having to SI a lot more. interesting also that Andrea wins the
> race, in spite of poorer SO choices and more swap traffic overall.
>
> > Neadless to say that while running the test on either box, the entire
> > computer became unresponsive multiple times for extended lengths of
> > times.
>
> yes, unfortunately this corrupts the value of the data, since the
> timecourses are not really comparable, and samples are only vaguely related
> to time...

If you miss anything you miss the plateu data that would be found when the
IO peaks. But i doubt much at all was really lost in this case.
> regards, mark hahn.

Actually i found that most if not all of the vmstat's that weren't being
displayed were displayed immediately after the "locks", ie. I got flooded
with vmstats upon the computer becoming responsive again.
Of course I should have been timing each run with a stopwatch, but that never
crossed my mind that the vmstat would be lost. In other words i thought of
it as analogous to having burst-lag on irc. Guess that's for tomorrow after
work.
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