Re: kswapd taking 100% CPU - only there's no swap?

[Arjan van de Ven <arjan infradead org>]

> Thanks Arjan!
> 
> I'd still love to hear more about why it's a bad idea to have no swap, 
> particularly given the number of diskless nodes we have and plan to 
> deploy.  Apparently my swap knowledge is lacking.  :)


by removing all swap, you take away the VM's breathing room.
The VM may need to move memory around (for example because of physical
limits of some devices that can't do DMA to part of your memory), or
temporarily park some memory to make progress. If you take away this bit
of freedom from the VM, you make the VM's job a LOT harder. If you
compare the VM with a car driver with a seatbelt, you could compare a VM
without swap with a car driver with a straightjacket. Sure you can
drive, as long as it's in a straight line ;)

if you go diskless one  of the options is to make a small ramdisk and
put the swap in that. Yes I know it sounds silly... but... it gives that
freedom to the VM.