cvs commit: src/sys/kern kern_sig.c

David Schultz das at FreeBSD.ORG
Sat Mar 5 19:55:10 GMT 2005

On Sat, Mar 05, 2005, Peter Jeremy wrote:
> On Fri, 2005-Mar-04 18:47:04 -0500, David Schultz wrote:
> >vm.swap_enabled *does* control kstack swapping only.
> Not according to it's documentation: "Enable entire process swapout".
> And based on a quick check of the code I can't see anything in the
> code path that restricts vm.swap_enabled to kstacks only.

``Entire process'' used to mean the U-area and kstack, I think,
but we don't have a U-area anymore, so vm.swap_enabled basically
just controls the kstack swapping.  The only extra thing the
swapper does that the sysctl turns off is deactivate some pages in
processes that have already had their kstack swapped out or have
exceeded their rlimits.  But it just unmaps those pages and makes
them more likely to be paged out; it doesn't actually push them
out of core.

> That said, the option "NO_SWAPPING" does state that it controls
> swapping of stack pages only but appears to implement a superset of
> vm.swap_enabled.

No, I believe NO_SWAPPING is just the compile-time version of

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