Commit 48cdd828 authored Mar 13, 2012 by Konrad Rzeszutek Wilk

xen/cpufreq: Disable the cpu frequency scaling drivers from loading.



By using the functionality provided by "[CPUFREQ]: provide
disable_cpuidle() function to disable the API."

Under the Xen hypervisor we do not want the initial domain to exercise
the cpufreq scaling drivers. This is b/c the Xen hypervisor is
in charge of doing this as well and we can end up with both the
Linux kernel and the hypervisor trying to change the P-states
leading to weird performance issues.

Acked-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
[v2: Fix compile error spotted by Benjamin Schweikert <b.schweikert@googlemail.com>]

parent 448c8b1d

arch/x86/xen/setup.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -10,6 +10,7 @@
		#include <linux/pm.h>
		#include <linux/memblock.h>
		#include <linux/cpuidle.h>
		#include <linux/cpufreq.h>

		#include <asm/elf.h>
		#include <asm/vdso.h>
		@@ -420,6 +421,7 @@ void __init xen_arch_setup(void)
		boot_cpu_data.hlt_works_ok = 1;
		#endif
		disable_cpuidle();
		disable_cpufreq();
		WARN_ON(set_pm_idle_to_default());
		fiddle_vdso();
		}

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