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

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Modern POS systems • Many based on Intel Architecture and a variation of the standard “PC” platform. • Wide array of unusual on-board and off-board peripherals • Magstripe readers • PIN entry devices • Receipt printers • Touchscreens • Multiple displays • Cash drawers • Most commonly wall-socket powered with a local UPS for emergency operation. • Large retailers network POS devices. 4
<strong>Power</strong> is a large factor in operation costs • <strong>Power</strong> efficiency saves big money • Drop power usage 33% on 5000 terminals: Save $1 million in 7 years. • <strong>Power</strong> efficiency is on the mind of POS system purchasers • Retailers consider energy efficiency as a factor when selecting POS systems: Big Box: over 70% Grocery: over 50% Small Box: over 50% • As retail hours stretch... • Basic on/off power saving is limited. • Only 50% of big box retailers use on/off. • Saving power while open for business is essential. 5
Page 1 and 2: Embedded L
Page 3: Why care about Power</stron
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 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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