Linked by Thom Holwerda on Mon 23rd Apr 2012 16:29 UTC
Mac OS X Adam Fields and Perry Metzger have been investigating the serious performance issues people are experiencing with Lion. "Frequent beachballs, general overall slowness and poor UI responsivness, specific and drastic slowdowns on every Time Machine run, high memory utilization in Safari Web Content, mds, and kernel_task processes, large numbers of page outs even with a good deal of available RAM, and high amounts of RAM marked as inactive which is not readily freed back to other applications, with page outs favored." Apparently the issue is that the "virtual memory manager is bad at managing which pages should be freed from the inactive state and which ones should be paged out to disk". I won't make myself popular with a certain part of our readership, but really, is this considered a new problem? Mac OS X has always had terrible memory management, and where Windows has continuously become better at it, Mac OS X seems to have been stagnant and even getting worse. This is what happens when the company earns 2/3s of its revenue somewhere else.
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RE[2]: BSD Bug Reports?
by galvanash on Mon 23rd Apr 2012 23:15 UTC in reply to "RE: BSD Bug Reports?"
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I'm quite sure that the memory manager of OSX wasn't derived from BSD, but from Mach. Actually, FreeBSD has adapted that memory manager, so it's rather the other way around.

That was ages ago... FreeBSD inherited its Virtual Memory Management system from the original Berkeley codebase, which itself was modeled after the Mach VMM - but that was back in the 80s.

Afaik the two codebases haven't seen each other for nearly 30 years. At this point I would say they are probably still architecturally similar but completely different when it comes to the nuts and bolts of how they are implemented. Mach has stagnated for the last 20 years or so - BSD has not.

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