I saw 348591 while filing this. I do have a multicore maxchine, the widget shows the check box for multiple CPUs, but it is grayed out, and doesn't allow me to tick the multi-CPU option. dmesg: ... [ 0.201025] #2 #3 [ 0.205722] x86: Booted up 1 node, 4 CPUs
Just to add: it is a regression, on kubuntu 14.04, that is Plasma 4, it worked without problems, on that same machine. It is only after the upgrade to Plasma 5 that it stopped showing.
*** This bug has been marked as a duplicate of bug 366324 ***