Re: graphical swap comparison of aa and rik vm

Mark Hahn (hahn@physics.mcmaster.ca)
Thu, 1 Nov 2001 01:23:47 -0500 (EST)


> 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...

regards, mark hahn.

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