Re: [gentoo-user] Re: Disabling swap & mounting /tmp on tmpfs = new standard?

[Volker Armin Hemmann]

On Sonntag 31 Mai 2009, Grant wrote:
> >>>> I recently disabled swap and mounted /tmp on tmpfs for a netbook since
> >>>> the SSD is so slow, and now I'm wondering if that would be a wise move
> >>>> for all of my Gentoo systems.  In what type of situation would it be a
> >>>> bad idea?
> >>>
> >>> Instead of disabling swap, just make it small (like 32MB or something;
> >>> whatever the smallest allowable partition size is).  The kernel needs
> >>> swap to operate optimally, even if it's extremely small.  Just make
> >>> sure it's there.
> >>
> >> Hmm, on this old box I noticed swap was using more than 135,000K earlier
> >> today as I was emerging xulrunner and ImageMagick.  I think that the
> >> size of swap is relevant to the memory size that the box in question
> >> has.  Not all machines have found their way to 2G RAM yet ... ;)
> >
> > Don't forget that you can set swapiness too.  This is set in
> > /etc/sysctl.conf and for mine I have this:
> >
> > vm.swappiness = 30
> >
> > The lower the number, the less chance of it using swap.  If it is set to
> > 90, it will use a lot of swap which is fine if you have little ram or a
> > really fast drive.  If it is set to 30, then it will not use swap unless
> > it is basically out of ram.
> >
> > With the setting of 30, mine uses swap when compiling OOo or some other
> > large package or if I am opening a TON of pics.  Otherwise, swap is at 0
> > or close to it even after being up a long time.  I have 2Gbs here tho.
> > Your mileage may vary.
> >
> > Dale
>
> Thanks Dale.  Should "vm.swappiness = 30" work well on all systems?
> My Gentoo systems have vastly different specs and duties so I love
> tweaks that always improve things.  It sounds like /tmp on tmpfs is
> one of those.
>
> - Grant

you can set swappiness = 0 which works even better, because the kernel will 
only swap if it really has too.