Comment 7 for bug 355232
Revision history for this message
| David Gaarenstroom (david-gaarenstroom) wrote | #7 |
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(Get the code!)
For what it's worth, it is in commit 495f78bd6d8f7a5
UBUNTU: Build in CPU Frequency scaling drivers
Selecting the right CPU Frequency scaling driver is complicated from
userspace, involing a nasty shell script that attempts to guess by
grepping through /proc.
The kernel drivers themselves can adequately determine whether they
should be used, building them into the kernel will automatically select
the right one.
These aren't something you would want to unload either, you would
instead simply change the governor.
rtg - Added debian/
Signed-off-by: Scott James Remnant <email address hidden>
Signed-off-by: Tim Gardner <email address hidden>
- First of all, the kernel does not (and simply cannot) always adequately determine which one is the best driver to use for someones hardware (especially when choosing between speedstep-centrino and cpufreq-acpi). And even if it does, so would lets-modprobe-
- They are something you would want to unload in realistic situations, especially since:
* Some people prefer NOT to have a cpufreq driver, that's why it is a config option in the first place. There are systems known to consistently trigger a "pending-bit stuck" when using the powernow-k8 driver.
* AFAIK the Ubuntu team wants to achieve a faster boottime, not slower. Compiling in all drivers slow down booting noticeably. You don't need them to boot either, so they can be postponed until a bit later.
* Newer processors may not be supported until a new kernel is distributed, unless a custom module can be loaded. This is true for AMD 0xf family processors with more than 1 low power state. Also for all Black Edition AMD processors, the powernow-k8 driver does not support using their unlocked multiplier and probably never will because AMD doesn't want that feature in their powernow-k8 driver. The Linux-PHC project provides such drivers that can be installed/
* You may want to use a modified module, that enables undervolting, to maximize their battery life or reduce extreme heat by reducing the processor's power consumption. The Linux-PHC project provides such drivers. There is a large audience that uses them...