diff options
Diffstat (limited to 'Documentation/cpu-freq')
| -rw-r--r-- | Documentation/cpu-freq/cpu-drivers.txt | 9 | ||||
| -rw-r--r-- | Documentation/cpu-freq/governors.txt | 27 |
2 files changed, 32 insertions, 4 deletions
diff --git a/Documentation/cpu-freq/cpu-drivers.txt b/Documentation/cpu-freq/cpu-drivers.txt index 72f70b16d299..a3585eac83b6 100644 --- a/Documentation/cpu-freq/cpu-drivers.txt +++ b/Documentation/cpu-freq/cpu-drivers.txt @@ -108,8 +108,9 @@ policy->governor must contain the "default policy" for cpufreq_driver.target is called with these values. -For setting some of these values, the frequency table helpers might be -helpful. See the section 2 for more information on them. +For setting some of these values (cpuinfo.min[max]_freq, policy->min[max]), the +frequency table helpers might be helpful. See the section 2 for more information +on them. SMP systems normally have same clock source for a group of cpus. For these the .init() would be called only once for the first online cpu. Here the .init() @@ -184,10 +185,10 @@ the reference implementation in drivers/cpufreq/longrun.c As most cpufreq processors only allow for being set to a few specific frequencies, a "frequency table" with some functions might assist in some work of the processor driver. Such a "frequency table" consists -of an array of struct cpufreq_freq_table entries, with any value in +of an array of struct cpufreq_frequency_table entries, with any value in "index" you want to use, and the corresponding frequency in "frequency". At the end of the table, you need to add a -cpufreq_freq_table entry with frequency set to CPUFREQ_TABLE_END. And +cpufreq_frequency_table entry with frequency set to CPUFREQ_TABLE_END. And if you want to skip one entry in the table, set the frequency to CPUFREQ_ENTRY_INVALID. The entries don't need to be in ascending order. diff --git a/Documentation/cpu-freq/governors.txt b/Documentation/cpu-freq/governors.txt index e3e5d9ae50cd..219970ba54b7 100644 --- a/Documentation/cpu-freq/governors.txt +++ b/Documentation/cpu-freq/governors.txt @@ -167,6 +167,27 @@ of load evaluation and helping the CPU stay at its top speed when truly busy, rather than shifting back and forth in speed. This tunable has no effect on behavior at lower speeds/lower CPU loads. +powersave_bias: this parameter takes a value between 0 to 1000. It +defines the percentage (times 10) value of the target frequency that +will be shaved off of the target. For example, when set to 100 -- 10%, +when ondemand governor would have targeted 1000 MHz, it will target +1000 MHz - (10% of 1000 MHz) = 900 MHz instead. This is set to 0 +(disabled) by default. +When AMD frequency sensitivity powersave bias driver -- +drivers/cpufreq/amd_freq_sensitivity.c is loaded, this parameter +defines the workload frequency sensitivity threshold in which a lower +frequency is chosen instead of ondemand governor's original target. +The frequency sensitivity is a hardware reported (on AMD Family 16h +Processors and above) value between 0 to 100% that tells software how +the performance of the workload running on a CPU will change when +frequency changes. A workload with sensitivity of 0% (memory/IO-bound) +will not perform any better on higher core frequency, whereas a +workload with sensitivity of 100% (CPU-bound) will perform better +higher the frequency. When the driver is loaded, this is set to 400 +by default -- for CPUs running workloads with sensitivity value below +40%, a lower frequency is chosen. Unloading the driver or writing 0 +will disable this feature. + 2.5 Conservative ---------------- @@ -191,6 +212,12 @@ governor but for the opposite direction. For example when set to its default value of '20' it means that if the CPU usage needs to be below 20% between samples to have the frequency decreased. +sampling_down_factor: similar functionality as in "ondemand" governor. +But in "conservative", it controls the rate at which the kernel makes +a decision on when to decrease the frequency while running in any +speed. Load for frequency increase is still evaluated every +sampling rate. + 3. The Governor Interface in the CPUfreq Core ============================================= |