|| ||"Pallipadi, Venkatesh" <email@example.com>|
|| ||<firstname.lastname@example.org>, <email@example.com>,
|| ||[PATCHSET] 0/3 Dynamic cpufreq governor and updates to ACPI P-state driver|
|| ||Mon, 20 Oct 2003 19:56:07 -0700|
|| ||"Nakajima, Jun" <firstname.lastname@example.org>,
"Mallick, Asit K" <email@example.com>,
"Dominik Brodowski" <firstname.lastname@example.org>|
Most of the latest CPUs (laptop CPUs in particular) have feature
which enable very low latency P-state transitions
(like Enhanced Speedstep Technology-EST). Using this feature,
we can have a lightweight in kernel cpufreq governor,
to vary CPU frequency depending on the CPU usage. The
advantage being low power consumption and also cooler laptops.
Another related change is enhancing the current ACPI P-state
driver to handle:
EST (and MSR based P-state transitions), make the driver SMP
aware and introduce HT coordination in the driver (HT siblings
share the same CPU frequency).
The patches that follow this mail addresses the above issues.
They are against 2.6-test7 kernel. Many thanks to Dominik for
his comments and suggestions.
The patches will work on all laptops with EST technology
(Centrino) and also on any other system that supports low
latency frequency change.
Reviews/testing of patches are most welcome.
Patches are split as follows:
Patch 1/3: Changes to ACPI P-state driver, to handle MSR
based transitions frequency transitions and make the driver
Patch 2/3: Introduce HT-synchronization in the ACPI P-state
Driver, to take care of shared CPU frequency between HT siblings.
Patch 3/3: New dynamic cpufreq driver (called
DemandBasedSwitch driver), which periodically monitors CPU
usage and changes the CPU frequency based on the demand.
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