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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Um, not OS X only...
by remenic on Tue 24th Apr 2012 06:17 UTC
remenic
Member since:
2005-07-06

Linux has the same problems. Try unparring and unrarring a 10GB file, and look at how all of your memory gets paged out, in favor of storing that 10GB file in file buffers. Your 8GB box will crawl.

It's rediculous, but I believe it *still* happens. The kernel isn't to blame though, since it offers API's that prevent buffering/caching the file. Sadly, it's rarely used.

I guess Time machine doesn't or can't similar mechanisms.

API's:
http://linux.die.net/man/2/madvise MADV_DONTNEED
http://linux.die.net/man/2/posix_fadvise POSIX_FADV_DONTNEED

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