-.. BSD LICENSE
- Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
- All rights reserved.
-
- Redistribution and use in source and binary forms, with or without
- modification, are permitted provided that the following conditions
- are met:
-
- * Redistributions of source code must retain the above copyright
- notice, this list of conditions and the following disclaimer.
- * Redistributions in binary form must reproduce the above copyright
- notice, this list of conditions and the following disclaimer in
- the documentation and/or other materials provided with the
- distribution.
- * Neither the name of Intel Corporation nor the names of its
- contributors may be used to endorse or promote products derived
- from this software without specific prior written permission.
-
- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+.. SPDX-License-Identifier: BSD-3-Clause
+ Copyright(c) 2010-2014 Intel Corporation.
Power Management
================
-The Intel® DPDK Power Management feature allows users space applications to save power
+The DPDK Power Management feature allows users space applications to save power
by dynamically adjusting CPU frequency or entering into different C-States.
* Adjusting the CPU frequency dynamically according to the utilization of RX queue.
* scaling_setspeed
-In the Intel® DPDK, scaling_governor is configured in user space.
+In the DPDK, scaling_governor is configured in user space.
Then, a user space application can prompt the kernel by writing scaling_setspeed to adjust the CPU frequency
according to the strategies defined by the user space application.
-------------------------------------
Core state can be altered by speculative sleeps whenever the specified lcore has nothing to do.
-In the Intel® DPDK, if no packet is received after polling,
+In the DPDK, if no packet is received after polling,
speculative sleeps can be triggered according the strategies defined by the user space application.
+Per-core Turbo Boost
+--------------------
+
+Individual cores can be allowed to enter a Turbo Boost state on a per-core
+basis. This is achieved by enabling Turbo Boost Technology in the BIOS, then
+looping through the relevant cores and enabling/disabling Turbo Boost on each
+core.
+
+Use of Power Library in a Hyper-Threaded Environment
+----------------------------------------------------
+
+In the case where the power library is in use on a system with Hyper-Threading enabled,
+the frequency on the physical core is set to the highest frequency of the Hyper-Thread siblings.
+So even though an application may request a scale down, the core frequency will
+remain at the highest frequency until all Hyper-Threads on that core request a scale down.
+
API Overview of the Power Library
---------------------------------
* **Freq set**: Prompt the kernel to set the frequency for the specific lcore.
+* **Enable turbo**: Prompt the kernel to enable Turbo Boost for the specific lcore.
+
+* **Disable turbo**: Prompt the kernel to disable Turbo Boost for the specific lcore.
+
User Cases
----------
References
----------
-* l3fwd-power: The sample application in Intel® DPDK that performs L3 forwarding with power management.
+* l3fwd-power: The sample application in DPDK that performs L3 forwarding with power management.
-* The "L3 Forwarding with Power Management Sample Application" chapter in the *Intel® DPDK Sample Application's User Guide*.
+* The "L3 Forwarding with Power Management Sample Application" chapter in the *DPDK Sample Application's User Guide*.