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Old 11 May 2017, 10:13   #223
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Originally Posted by wawa View Post
yeah. for some curious reason. avail works under aros just fine.
Avail works just fine under OS4 too, but the results may be different to what you might expect because the memory allocation strategy is different to that of OS3. "Slab" allocation means that large chunks of RAM aren't returned to the free memory list until actually needed - kind of like how libraries aren't immediately flushed by OS3, but on a larger scale. IIRC the Avail Flush argument doesn't do anything on OS4 for this reason.

Originally Posted by grelbfarlk View Post
Compare away how much RAM is used booting WB1.3 in a base A500.
Base machines generally have the advantage that almost the entire OS is in ROM, which means it doesn't need to be stored in RAM. If that was needed, the RAM usage would be close to 60%.

As wawa said, anyone who wants more than a base machine probably has more RAM at this stage, so it's kind of a silly discussion, especially given that so many people are more than happy to hand over 0.5 or 1MB of fast RAM for a copy of Kickstart in order to speed up access, and even more for loading replacement modules via OS 3.9 or Blizkick. 1.5MB seems pretty reasonable in comparison.

OS4's high initial usage might be a combination of several things - Picasso96, the USB stack and various other modules that would be loaded later during a full boot on OS3 are a part of Kickstart under OS4, so are loaded and running before the startup-sequence is executed. Two 68k emulators are also loaded at this stage stage. And by default there are heaps of drivers loaded into RAM as part of Kickstart that aren't necessarily required - various PCI storage drivers, graphics card drivers and so on. And the slab allocation system mentioned above tends to cache objects, not releasing the RAM until you're running out. So you might find that if you get your free RAM down to a few MB, you can still allocate larger chunks than you think as some of the cached objects are expunged.
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