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

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cpufreq Notifications • Your driver can register with cpufreq to get notified of power events: • CPUFREQ_PRECHANGE: sent immediately before a new operating point is set • CPUFREQ_POSTCHANGE: sent immediately after a new operating point is set • CPUFREQ_RESUMECHANGE: sent if the cpufreq subsystem determines that an operating point was changed during system suspend
Define <strong>Power</strong> <strong>Management</strong> Policies Before we get into that we'd better learn what we can control and how we can control it • Saving power while the CPU is active • Voltage and frequency scaling of the CPU using cpufreq • Saving power while the CPU is inactive • Idle scaling • Dynamic tick • Deferrable timers • Mitigate wakeups using <strong>Power</strong>Top and system tuning 33
Page 1 and 2: Embedded L
Page 3 and 4: Why care about Power</stron
Page 5 and 6: Power is a large f
Page 7 and 8: How we save power Two big ways: •
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 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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