PowerTOP v2.0 Release [LWN.net]

PowerTOP v2.0 Release

Posted May 11, 2012 5:33 UTC (Fri) by bmenrigh (subscriber, #63018)
In reply to: PowerTOP v2.0 Release by sheepdestroyer
Parent article: PowerTOP v2.0 Release

It's certainly not comprehensive but I have a script to turn a bunch of settings on:

lambda ~ # cat scripts/power_save_on.sh
#!/bin/bash

# SCSI
find /sys/class/scsi_host | egrep '\/host[0-9]+$' | while read LINE; do echo 'min_power' > ${LINE}'/link_power_management_policy'; done

# Device power savings
find /sys/bus/{pci,i2c}/devices/*/power/control | while read LINE; do echo 'auto' > ${LINE}; done

# USB
find /sys/bus/usb/devices/*/power/control | while read LINE; do echo 'auto' > ${LINE}; done

# WOL
ethtool -s eth0 wol d

# sysctl settings
sysctl -p > /dev/null

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PowerTOP v2.0 Release

Posted May 11, 2012 6:04 UTC (Fri) by sheepdestroyer (subscriber, #54968) [Link]

It works great, many thanks
the only settings remaining in the 'bad' state after executing it are :

Bad Wireless Power Saving for interface wlan0
Bad NMI watchdog should be turned off
Bad Power Aware CPU scheduler
Bad VM writeback timeout
Bad Enable Audio codec power management

Someone know about this Power Aware CPU scheduler? It seems I never heard about it outside PowerTop.

PowerTOP v2.0 Release

Posted May 11, 2012 6:40 UTC (Fri) by zlynx (subscriber, #2285) [Link]

I think that it means the scheduler settings which try to control core and hyper-threading usage.

There are two of them. I think one controls if threads are concentrated on one core until it is overloaded, or spread out to all cores evenly. The other one is similar but controls if threads are scheduled on hyperthread siblings first, or scheduled on really separate cores.

PowerTOP v2.0 Release

Posted May 11, 2012 7:19 UTC (Fri) by sheepdestroyer (subscriber, #54968) [Link]

OK so i've now added the following comands to your script witch activate the last 'bad' knob i've had :

# enable the power aware CPU scheduler
echo 1 > /sys/devices/system/cpu/sched_mc_power_savings

# enable HD audio powersave mode
echo 1 > /sys/module/snd_hda_intel/parameters/power_save

# Increase the VM dirty writeback time from 5.00 to 15 seconds with:
echo 1500 > /proc/sys/vm/dirty_writeback_centisecs
# This wakes the disk up less frequently for background VM activity

# Disable NMI Watchdog
echo 0 > /proc/sys/kernel/nmi_watchdog

# Enable Laptop Mode - this one is a bonus
echo "5" > /proc/sys/vm/laptop_mode