Dave abrahams: â†Created page with '== Synopsys == One good way to save power with a dynticks-enabled kernel is to set [http://www.lesswatts.org/tips/disks.php SATA link power management] to minimum pow...'

2008-05-05T00:18:53Z

â†Created page with '== Synopsys == One good way to save power with a dynticks-enabled kernel is to set [http://www.lesswatts.org/tips/disks.php SATA link power management] to minimum pow...'

New page

== Synopsys ==

One good way to save power with a [[dynticks]]-enabled kernel is to set [http://www.lesswatts.org/tips/disks.php SATA link power management] to minimum power. However, if you do that you will probably experience long delays when resuming from suspend-to-disk. If, like {{Ubuntu}} Hardy, your distribution uses <tt>pm-suspend</tt>, the following script placed in <tt>/etc/pm/sleep.d/99sata</tt> will set the link power to maximum performance just before suspending, and restore it to whatever it was upon resume.

<pre>
#!/bin/bash

[ -d /sys/class/scsi_host/ ] || exit 0

. /usr/lib/pm-utils/functions

suspend_sata()
{
pushd /sys/class/scsi_host/ > /dev/null 2>&1
local host
for host in $(ls -1); do
if [ -e ${host}/link_power_management_policy ]; then
local policy=$(cat ${host}/link_power_management_policy)
savestate ${host}_link_power_management_policy "${policy}"
echo max_performance > ${host}/link_power_management_policy
fi
done
popd
}

resume_sata()
{
pushd /sys/class/scsi_host/ > /dev/null 2>&1
local host
for host in $(ls -1); do
if [ -e ${host}/link_power_management_policy ]; then
local policy=$(restorestate $(echo ${host}_link_power_management_policy))
echo ${policy} > ${host}/link_power_management_policy
fi
done
popd
}

case "$1" in
suspend|hibernate)
suspend_sata
;;
resume|thaw)
resume_sata
;;
*)
;;
esac

exit $?
</pre>

Suspend/Resume Support For SATA Link Power Management - Revision history

Dave abrahams: â†Created page with '== Synopsys == One good way to save power with a dynticks-enabled kernel is to set [http://www.lesswatts.org/tips/disks.php SATA link power management] to minimum pow...'

Dave abrahams: â†Created page with '== Synopsys == One good way to save power with a dynticks-enabled kernel is to set [http://www.lesswatts.org/tips/disks.php SATA link power management] to minimum pow...'