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Re: Linux compat and swap

On Fri, 24 Apr 2020 00:50:38 -0700
"Greg A. Woods" <> wrote:

> On the other hand the vm.*max percentages are just limits to how many
> pages will be reclaimed from other uses when a given category faces
> pressure from extensive and immediate use -- they do not set the
> maximum use for a given category.  On my rsync backup host I normally
> see 85% of pages allocated to file cache even though vm.filemax is
> just 50.

But what is the value of vm.filemax? It tells the system what
percentage of memory to steal from other uses, but this is counter
productive, since by stealing from vm.anon and vm.exec it can result in
swapping and extra disk I/O, which is what vm.filemax is trying to
avoid in the first place, that is unnecessary disk I/O.

I think the behaviour needs fixing, i.e. if vm.filemax is about to push
pages to swap, then it should stop.

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