Description of problem:
Starting with kernel-rt-3.10.0-439.rt56.327.el7, we now have CONFIG_RCU_NOCB_CPU_NONE=y (instead of CONFIG_RCU_NOCB_CPU_ALL=y). This means that we're required to specify no-CBs CPUs with rcu_nocbs=. Otherwise we'll run into spikes.
The [bootloader] section in both guest and host tuned.conf must have the following option:
Version-Release number of selected component (if applicable): tuned-2.5.1-7.el7.noarch
Two additional notes:
- I'm not sure if the realtime profile should get this option too (probably yes)
- There seems to be a bug with CONFIG_RCU_NOCB_CPU_NONE=y where processes get stuck in D state during system boot. This issue is workarounded by rcu_nocbs=
I guess this is dupe of bug 1334479. If not, please reopen.
*** This bug has been marked as a duplicate of bug 1334479 ***