Comment 278 for bug 1690085

(In reply to Chris Hall from comment #192)
> OK...
>
> []# cat /proc/cmdline
> BOOT_IMAGE=/vmlinuz-4.15.3-300.fc27.x86_64 root=... ro rhgb quiet
> rcu_nocbs=0-15 processor.max_cstate=5
>
> []# python zenstates.py -l
> P0 - Enabled - FID = 90 - DID = 8 - VID = 20 - Ratio = 36.00 - vCore =
> 1.35000
> P1 - Enabled - FID = 80 - DID = 8 - VID = 2C - Ratio = 32.00 - vCore =
> 1.27500
> P2 - Enabled - FID = 84 - DID = C - VID = 68 - Ratio = 22.00 - vCore =
> 0.90000
> P3 - Disabled
> P4 - Disabled
> P5 - Disabled
> P6 - Disabled
> P7 - Disabled
> C6 State - Package - Enabled
> C6 State - Core - Enabled
>
> So... kernel command line option "processor.max_cstate=5" does not appear to
> disable C6. [And removing the option did not seem to change anything,
> either.]
>
> But...
>
> []# python zenstates.py --c6-disable
> Disabling C6 state
>
> []# python zenstates.py -l
> P0 - Enabled - FID = 90 - DID = 8 - VID = 20 - Ratio = 36.00 - vCore =
> 1.35000
> P1 - Enabled - FID = 80 - DID = 8 - VID = 2C - Ratio = 32.00 - vCore =
> 1.27500
> P2 - Enabled - FID = 84 - DID = C - VID = 68 - Ratio = 22.00 - vCore =
> 0.90000
> P3 - Disabled
> P4 - Disabled
> P5 - Disabled
> P6 - Disabled
> P7 - Disabled
> C6 State - Package - Disabled
> C6 State - Core - Disabled
>
> So... having added "python zenstates.py --c6-disable" to rc.local
> (eventually), I now appear to have C6 disabled when the system is rebooted.
>
> Do I have to do anything else to make sure that C6 *stays* disabled ?
>
> Chris

If you suspend your system, make sure you run zenstates again upon resume. Otherwise you should be ok.