Embedded Linux Power Management on the Intel Atom ... - MontaVista

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So let's get started... • <strong>Power</strong> management is a system level design goal... not a software level design goal. 6
How we save power Two big ways: • Turn stuff off • Clock trees, caches, displays, radios, USB, memory, anything you can get your hands on. • Clock stuff down and power it at a lower voltage • P = CV 2 f in CMOS • Switching capacitance • Voltage (which also relates to frequency) • Frequency • Question #1: How does the software find out what the hardware can do and how to tweak it? • Systems designed to be “PC” compatible do this very differently 7
Page 1 and 2: Embedded L
Page 3 and 4: Why care about Power</stron
Page 5: Power is a large f
Page 9 and 10: ACPI / cpufreq Software Architectur
Page 11 and 12: ACPI • ACPI is an open-industry s
Page 13 and 14: What is Deep Power
Page 15 and 16: L2 Dynamic Cache Sizing OS ACPI 8-W
Page 17 and 18: Enumerate System Devices You'll nee
Page 19 and 20: Identify Constraints Are there rela
Page 22 and 23: Define Power <stro
Page 24 and 25: Stitching it together • CPUfreq
Page 26 and 27: The Governor • Task: Decide how a
Page 28 and 29: ondemand Governor Example
Page 30 and 31: Making Drivers Power</stron
Page 32 and 33: cpufreq Notifications • Your driv
Page 34 and 35: Saving power during idle • Idle S
Page 36 and 37: Mitigate wakeups with Power
Page 38 and 39: Free for the asking... “MontaVist

Embedded Linux Power Management on the Intel Atom ... - MontaVista

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