Re: Linux compat and swap

[tlaronde%polynum.com@localhost]

On Fri, Apr 24, 2020 at 03:35:15PM -0700, Greg A. Woods wrote:
> At Fri, 24 Apr 2020 14:56:37 +0200, tlaronde%polynum.com@localhost wrote:
> Subject: Re: Linux compat and swap
> >
> > Does somebody know what are the main source files implementing it so
> > that if no in depth documentation is available, the C files would give
> > the picture?
> 
> again, from my sysctl.conf:  :-)
> 
> # See also:
> #
> # http://web.archive.org/web/20181008110324/http://www.selonen.org/arto/netbsd/vm_tune.html
> # http://chuck.cranor.org/p/diss.pdf
> # http://usenix.org/publications/library/proceedings/usenix99/full_papers/cranor/cranor.pdf
> 
> 
> BTW, I've used the settings I posted basically since UVM was integrated
> on all my servers, and even on some small machines like a little Soekris
> board with 512MB of RAM.
> 
> In hindsight I think the vm.exec* values are a bit too high for most
> uses, but at the same time they don't seem to hurt for the kinds of uses
> I put my machines to.  I admit though I haven't extremely stressed any
> smaller machines (virtual or otherwise) to see how they do.  The domU I
> edit/email/build on has 8GB assigned, and though it runs with a fair
> number of pages out on swap, it never thrashes even with "-j 12" builds.
> (and that's with a fully static-linked userland too)
> 
> I would say generally speaking that UVM does better than any other VM
> management system I've used, including even macOS with its compressed
> memory feature; though at some level macOS is hard to judge because of
> its massive overreliance on dynamic linking and zillions of frameworks.
> macOS only really starts to shine on 2+ CPU machines with SSD system
> storage.
> 
> Indeed I suspect adding compressed memory support to UVM, i.e. as an
> intermediate step before paging to disk, could make it the very best of
> the best (for multi-core SMP systems, at least, though even a single CPU
> can probably swap compressed pages faster than it can write and read
> them from spinning rust).
> 

Just to say thank you! and thank you to all who contributed to the
thread!

I did learn from it!

Best regards,
-- 
        Thierry Laronde <tlaronde +AT+ polynum +dot+ com>
                     http://www.kergis.com/
                       http://www.sbfa.fr/
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