[CPUFREQ] CPU frequency display in /proc/cpuinfo
authorVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Fri, 2 Dec 2005 18:43:20 +0000 (10:43 -0800)
committerDave Jones <davej@redhat.com>
Wed, 7 Dec 2005 03:35:11 +0000 (19:35 -0800)
commit95235ca2c20ac0b31a8eb39e2d599bcc3e9c9a10
treecdfbebe72a1563f1bfe16b0335da7f9ecb78a91d
parent9a7d82a89a8bf55b112f2a5c3b3f405eb95a4303
[CPUFREQ] CPU frequency display in /proc/cpuinfo

What is the value shown in "cpu MHz" of /proc/cpuinfo when CPUs are capable of
changing frequency?

Today the answer is: It depends.
On i386:
SMP kernel - It is always the boot frequency
UP kernel - Scales with the frequency change and shows that was last set.

On x86_64:
There is one single variable cpu_khz that gets written by all the CPUs. So,
the frequency set by last CPU will be seen on /proc/cpuinfo of all the
CPUs in the system. What you see also depends on whether you have constant_tsc
capable CPU or not.

On ia64:
It is always boot time frequency of a particular CPU that gets displayed.

The patch below changes this to:
Show the last known frequency of the particular CPU, when cpufreq is present. If
cpu doesnot support changing of frequency through cpufreq, then boot frequency
will be shown. The patch affects i386, x86_64 and ia64 architectures.

Signed-off-by: Venkatesh Pallipadi<venkatesh.pallipadi@intel.com>
Signed-off-by: Dave Jones <davej@redhat.com>
arch/i386/kernel/cpu/proc.c
arch/ia64/kernel/setup.c
arch/x86_64/kernel/setup.c
drivers/cpufreq/cpufreq.c
include/linux/cpufreq.h