From 35cb6ba080586b2b780b032650a816887e7ad96d Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Mon, 6 Feb 2012 08:17:11 -0800 Subject: [PATCH] ACPI: Do cpufreq clamping for throttling per package v2 commit 2815ab92ba3ab27556212cc306288dc95692824b upstream. On Intel CPUs the processor typically uses the highest frequency set by any logical CPU. When the system overheats Linux first forces the frequency to the lowest available one to lower the temperature. However this was done only per logical CPU, which means all logical CPUs in a package would need to go through this before the frequency is actually lowered. Worse this delay actually prevents real throttling, because the real throttle code only proceeds when the lowest frequency is already reached. So when a throttle event happens force the lowest frequency for all CPUs in the package where it happened. The per CPU state is now kept per package, not per logical CPU. An alternative would be to do it per cpufreq unit, but since we want to bring down the temperature of the complete chip it's better to do it for all. In principle it may even make sense to do it for all CPUs, but I kept it on the package for now. With this change the frequency is actually lowered, which in terms also allows real throttling to proceed. I also removed an unnecessary per cpu variable initialization. v2: Fix package mapping Signed-off-by: Andi Kleen Signed-off-by: Len Brown Signed-off-by: Greg Kroah-Hartman --- Reading git-format-patch failed