On Fri, Jun 27, 2008 at 05:13:24PM +0100, Richard Hughes wrote:
At the moment we set:
# CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE is not set
CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE=y
# CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND is not set
# CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE is not set
CONFIG_CPU_FREQ_GOV_PERFORMANCE=y
CONFIG_CPU_FREQ_GOV_POWERSAVE=m
CONFIG_CPU_FREQ_GOV_USERSPACE=y
CONFIG_CPU_FREQ_GOV_ONDEMAND=m
CONFIG_CPU_FREQ_GOV_CONSERVATIVE=m
This is not ideal from a power-saving point of view.
In an ideal world we would:
* remove CONFIG_CPU_FREQ_GOV_CONSERVATIVE -- ondemand does a better job
on all workloads
* remove CONFIG_CPU_FREQ_GOV_USERSPACE -- we have nothing in userspace
that needs this sort of control, and if we did, the latency would be
horrible
needed for the cpuspeed governor
* remove CONFIG_CPU_FREQ_GOV_POWERSAVE -- ondemand automatically
throttles down to lowest, and is just a hardcoded state
* compile into the kernel CONFIG_CPU_FREQ_GOV_ONDEMAND -- we really
want to be running this on all systems that support it
* set ONDEMAND or PERFORMANCE to default as USERSPACE is just changed
to something else by cpuspeed. You really don't want to be using
USERSPACE at all.
Not all CPUs are capable of running ondemand because of the latency they
incur during transitions.
Matthew Garrett and I are working on a latency profile for power
management, and having all these modules potentially loaded is bad.
I don't follow this. Can you show whatever numbers you have that you're
basing this on ?
Dave
--
http://www.codemonkey.org.uk