Recent Intel CPUs provide both energy-saving and performance boost capabilities, respectively named SpeedStep and TurboBoost. These features change individual core frequency depending on system load. However, this may not have the desired outcome on high-performance servers.

Checking The Current Processor Speed

To check the current speed of your processor(s), type:

cat /proc/cpuinfo | grep MHz

For example:

cat /proc/cpuinfo  | grep MHz
cpu MHz   : 1400.000
cpu MHz   : 1400.000
cpu MHz   : 1400.000
cpu MHz   : 1400.000
cpu MHz   : 1400.000
cpu MHz   : 1400.000
cpu MHz   : 3500.000
cpu MHz   : 3500.000

Note above that only 2 cores are running at top speed (3500.000). While this may be a good use for power efficiency, it is not good for high performance servers such as LogZilla.

Running At Top Performance

The Linux kernel provides 4 profiles, named CPU governors named conservative, ondemand, userspace, and powersave performance

By default, Linux distributions set the ondemand governor. This governor is a good compromise between energy saving and performance-boosting as it adapts to the current CPU workload. Although, there are cases in which performance is heavily degraded on moderately loaded servers. We recommend using the performance governor instead.

Disabling SpeedStep/TurboBoost

Setting the CPU governor may be done using the following function. This function can either be pasted directly into an SSH session or placed in a .bash_aliases file. Note that this will only work like the root user.

function setgov ()
{
    # usage:
    # setgov ondemand
    # setgov performance
    echo "Current setting: $(cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor | sort -u)"
    echo "Current CPU Speeds:"
    cat /proc/cpuinfo | grep 'cpu MHz'
    [[ -z $1 ]] && { echo "Missing argument (ondemand|performance)"; return 1; }
    echo "$1" | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
    echo "New CPU Speeds:"
    cat /proc/cpuinfo | grep 'cpu MHz'
}

Once the function is in your .bash_aliases file, simply type source ~/.bash_aliases to load it, then run setgov. This will return something similar to:

root@myserver: # setgov
Current setting: ondemand
Current CPU Speeds:
cpu MHz     : 1400.000
cpu MHz     : 2300.000
cpu MHz     : 1400.000
cpu MHz     : 3500.000
cpu MHz     : 3500.000
cpu MHz     : 1700.000
cpu MHz     : 1400.000
cpu MHz     : 2300.000
Missing argument (ondemand|performance)

Running setgov performance will return something similar to:

root@myserver: # setgov performance
Current setting: ondemand
Current CPU Speeds:
cpu MHz     : 2900.000
cpu MHz     : 1400.000
cpu MHz     : 1700.000
cpu MHz     : 1400.000
cpu MHz     : 1400.000
cpu MHz     : 2300.000
cpu MHz     : 3500.000
cpu MHz     : 1400.000
performance
New CPU Speeds:
cpu MHz     : 3500.000
cpu MHz     : 3500.000
cpu MHz     : 3500.000
cpu MHz     : 3500.000
cpu MHz     : 3500.000
cpu MHz     : 3500.000
cpu MHz     : 3500.000
cpu MHz     : 3500.000

Permanent Change

The following commands (run as root) will permanently set the performance governor so that it keeps the setting after a reboot:

apt-get install cpufrequtils
echo 'GOVERNOR="performance"' >/etc/default/cpufrequtils 
service cpufrequtils reload

The governor may be changed at any time by altering the GOVERNOR variable above and reloading cpufrequtils.

TurboBoost only runs when other CPU cores are throttled (down), due to each CPU's Thermal Design Power (TDP). This implies that enabling performance governor will have each core running exactly at nominal frequency, and never above. TurboBoost depends on SpeedStep, thus disabling SpeedStep in BIOS will disable CPU throttling and TurboBoost