Solaris Power Aware Dispatcher and Deep C-State Support

This feature includes the following enhancements:

• Event driven CPU power management – On systems that support Dynamic Voltage and Frequency Scaling (DVFS) by Solaris, the kernel scheduler or dispatcher will schedule threads across the system's CPUs in a manner that coalesces load, and frees up other CPUs to be deeply power managed. CPU power state changes are triggered when the dispatcher recognizes that the utilization across a group of power manageable CPUs has changed in a significant way. This eliminates the need to periodically poll CPU utilizations across the system, and enables the system to save more power when CPUs are not used, while driving performance when CPUs are used. Event driven CPU power management is enabled by default on systems that support DVFS. This feature can be disabled, or the legacy polling-based CPU power management can be used through the cpupm keyword in power.conf(4).

• Support for Deep Idle CPU Power Management or deep C-state support on Intel Nehalem-based systems – The project also adds Solaris support for Deep C-states on Intel Nehalem-based systems. This support enables unused CPU resources to be dynamically placed in a state where they consume a fraction of the power consumed in their normal operating state. This feature also provides Solaris support for the power saving feature, as well as the policy implementation that decides when idle CPUs should request deep idle mode. This feature will be enabled by default where supported, and can be disabled through the cpu-deep-idle keyword in power.conf(4).

• Observability for Intel's Turbo Mode feature – Intel Nehalem-based systems have the ability to raise the operating frequency of a subset of the available cores when there is enough thermal headroom to do so. This ability temporarily boosts performance, but it is controlled by the hardware and transparent to software. Starting with the Solaris 10 5/09 release, a new kstat module observes when the system is entering the turbo mode and at which frequency it operates.