Re: [gentoo-user] 32GB RAM and Swap

[Michael]

On Saturday, 2 May 2020 09:53:06 BST Dale wrote:
> Wols Lists wrote:
> > On 01/05/20 21:29, Dale wrote:
> >> It gets really slow to respond when it uses swap but it beats crashing.
> >> Just set swapiness to a low number.  I think mine is set to 10.
> >>
> >> Given the cheapness of hard drives, I'm not sure why having several
> >> gigabytes of swap space is of much concern.  I have the same amount of
> >> ram as you and I have a 12GB swap space.  I use LVM so I can grow it if
> >> needed or just add another swap space.  I might add, I've seen times
> >> where it gets used.
> >
> > That first paragraph is why too much swap space is bad - if an app goes
> > rogue it can kill system response and make regaining control of the
> > system a nightmare.
> >
> > Accidentally or on purpose, if a system runs out of ram and starts
> > thrashing, you're in big trouble if it's an app eating memory like no
> > tomorrow.
> >
> > Cheers,
> > Wol
> >
> > .
>
> That's why I set swapiness to a low number.  I don't want it to use swap
> unless it is to prevent a crash.  If I set it to a higher number, it
> wants to use swap even when there is memory available.  Once it starts
> using swap, it gets slow.  The more it uses, the worse it gets.
> However, it beats it rebooting without umounting partitions and such.
> If nothing else, it may give me time to use the alt-sys sequence.
>
> I'm maxed out on memory at the moment but wish I could get and afford
> 64GBs, in a way.  Still, I'd have a swap partition.
>
> Dale
>
> :-)  :-)

I'd be interested to know as a comparison if Nikos' and Dale's I/O 
unresponsiveness in swapping sees an improvement with the I/O scheduler for 
spinning drives set to bfq; e.g.:

echo bfq > /sys/block/sda/queue/scheduler