On May 28, 2008, at 3:36 PM, Thomas Backman wrote:
This is very annoying... I rebooted 40 minutes ago. Since then I
started a VM with 640MB RAM (in VirtualBox, rather than VMware),
iTunes, Firefox etc. Current RAM stats:
Page outs: 25MB (it stopped paging when I quit Firefox)
Why is it swapping with 37% of my total RAM inactive?! I just
don't get it. Stuff starts beachballing at random, etc.
I'm starting to seriously consider switching to another OS because
of this. I can't use virtual machines anymore, and that's not the
only problem, either... Needless to say it happens without them,
too, sooner or later... :(
I realize this isn't really the "OS X support" list, just figured
people here might know what's going on.
Your presumptions about how VM [virtual memory] works on OS X are
inaccurate, which is resulting in misconceived beliefs as to what
occurring. You might consider reading Amit Singh's excellent Mac OS
X Internals book.
As for your "beachballs", these are (most generally speaking) not
caused by VM paging/swapping, but by other IO subsystem waits.
Indeed I'm not even sure VM paging could ever incur a beachball. If
you're seeing beachballs look for why your IO is stalling. "Spin
Control" can help you here.
If you're using virtual machines, this can explain, perhaps, why
you're seeing a high than normal incidence of beachballs since (a)
your IO subsystem isn't 'real', and (b) you have other virtual
machines competing for your real IO subsystem. Both of these could
contribute your your observed waits.
Again, "Spin Control", the tool, can assist you in determining what
these beachballs are caused by and could lead you to a solution.
And the "beach balls" are actually because the "are you alive?"
messages being sent to the applications run loop by the window
server (which is what controls the mouse curosor) are not responded
The "beach balls" are typically caused by doing blocking work in
your application run loop, instead of marshalling that work off to
another thread to get it completed there, instead. Because of that,
the run loop is not reentered at the top often enough to respond to
the events. So it's usually an indicator of an application design
Pot, meet kettle.
My MacBook Pro runs a vanilla collection of programs on OS X 10.5.2 --
Mail, Safari, Address Book, iTunes, TextWrangler. I don't have VMware
or Parallels or Boot Camp or any other virtual anything installed.
(And no, I don't run Time Machine at all; too many slowdowns.) I
maintain a very vanilla system. I keep it clean. I like simple,
Although the computer has 3GB of RAM, it readily goes into fits of
swapping. (Safari is an obvious culprit; it has a voracious appetite
for VM.) At the moment, the computer has 3GB of swap data spread
across 10 swap files. And, yes, I get beachballs from standard Apple
programs (Mail is especially likely to beachball). It's ironic that
my laptop is more prone to slowdowns than my Linux box, which has 1GB
of RAM. But I like the Apple user interface, so I tolerate the
swapping and the beachballs.
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