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: BSD Bug Reports?
by galvanash on Mon 23rd Apr 2012 23:06 UTC in reply to "BSD Bug Reports?"
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Has anyone checked out the BSD bug reports. The BSD guys are pretty good, so if this was broken when Apple forked Darwin from it, I am sure the BSD guys have fixed it by now. If Apple broke it after they got it, this proves that they shouldn't be mucking about with the internals, but instead, just grab a fresh copy of BSD and lay their UI on top of it again.

Darwin is basically OSX minus the GUI (kernel + userland). Darwin is not a fork of BSD - the parts of Darwin using BSD derived code were ported from FreeBSD.

The XNU kernel is not and never was based on the BSD kernel - it is a heavily modified Mach 3 kernel as was used in NextStep. There were some things done to the kernel to make it mesh better with a BSD userland, but it is still Mach under the hood.

In short there is quite a lot of BSD derived code in OSX, but very very little of it has anything to do with memory management - that is all done by Mach.

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