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re: Prefer pageing to swapping
I think the proposed patch already does that?
+ * try to keep 0.5% of available RAM free, but limit to between
+ * 128k and 1024k per-CPU. XXX: what are these values good for?
+ uvmexp.freemin = uvmexp.npages / 200;
+ uvmexp.freemin = MAX(uvmexp.freemin, (128*1024) >> PAGE_SHIFT);
+ uvmexp.freemin = MIN(uvmexp.freemin, (1024*1024) >> PAGE_SHIFT);
+ uvmexp.freemin *= ncpu;
So that's gonna peg at 1MB per CPU which (for lack of other evidence)
seems somewhat reasonable. I'd be curious to know the origin of the
original "between 16k and 256k" given the (pre-existing) "XXX: what are
these values good for?" comment.
those values came all the way from mach vm in pre-4.4bsd netbsd 0.0 days
as i recall, no one i've spoken to knows why they are those values.
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