SOLVED Tuning rc.conf

[spiceygas]

CPU: 2x Xeon 2680v3
Motherboard: X10DRi-T4+
Memory: 128 GB

I've got a relatively new bare metal deployment of FreeNAS. Thinking about ways to reduce power consumption when idle. I'll admit to being new to FreeBSD, so I'm hoping some community members can tell me if these changes are safe to make to rc.conf. Also, I've read on some other threads that rc.conf settings may be overridden by FreeNAS, so I'm not sure if changing this will even do anything.

Code:

# Use the lowest power state available
performance_cx_lowest="Cmax"

# Disable turbo boost
performance_cpu_freq="LOW"

 

[Spearfoot]

CPU: 2x Xeon 2680v3
Motherboard: X10DRi-T4+
Memory: 128 GB

I've got a relatively new bare metal deployment of FreeNAS. Thinking about ways to reduce power consumption when idle. I'll admit to being new to FreeBSD, so I'm hoping some community members can tell me if these changes are safe to make to rc.conf. Also, I've read on some other threads that rc.conf settings may be overridden by FreeNAS, so I'm not sure if changing this will even do anything.

Code:

# Use the lowest power state available
performance_cx_lowest="Cmax"

# Disable turbo boost
performance_cpu_freq="LOW"

You are correct -- FreeNAS will overwrite any manual changes you make to rc.conf, or most other system files.

However, you can use Tunables to change your system's behavior.

 

[spiceygas]

You are correct -- FreeNAS will overwrite any manual changes you make to rc.conf, or most other system files.

However, you can use Tunables to change your system's behavior.

That's helpful. I just read through the system documentation and it makes sense.

Any suggestion on whether the two rc.conf configuration changes in the first post are safe to make? I'm a FreeBSD noob, and don't want to break anything.

 

[Samuel Tai]

Should be safe enough, as rc.conf tunables don't take effect until the next reboot. If they don't work out, you can delete them from tunables and reboot again.

 

[spiceygas]

Yep, it worked fine after a reboot. Thank you for the help.

For anyone else who may stumble into this thread, I tested a couple options:

Code:

# Use minimum frequency the CPU can support
performance_cpu_freq="LOW"

# Disable turbo boost
performance_cpu_freq="NONE"

I think you can also set it to a specific numeric frequency, too, though I didn't have a reason to try that. Maybe in the future.

• Available frequencies for your CPU are available by running sysctl dev.cpu.0.freq_levels.
• You can see your current CPU frequency by running sysctl dev.cpu.0.freq.
• Tested on 2x Xeon 2680v3.