linux/drivers/cpufreq
Thomas Renninger cef9615a85 [CPUFREQ] ondemand: Uncouple minimal sampling rate from HZ in NO_HZ case
With this patch you have following minimal sampling rate restrictions:

Kernel restrictions:
If CONFIG_NO_HZ is set, the limit is 10ms fixed.
If CONFIG_NO_HZ is not set or no_hz=off boot parameter is used, the
limits depend on the CONFIG_HZ option:
HZ=1000: min=20000us  (20ms)
HZ=250:  min=80000us  (80ms)
HZ=100:  min=200000us (200ms)

HW restrictions:
Do not sample/poll more often than HW latency * 100  exported by the low
level cpufreq HW driver

The higher value of above restrictions is the minimal sampling rate
that can be set (and can be seen via ondemand/sampling_rate_min sysfs file)

Default sampling rate still is HW latency * 1000, but this will now end
up in lower values on latest (Intel and AMD) hardware as these can switch
really fast and sampling rate mostly was limited to the 80ms or 200ms
(depending on whether HZ=250 or HZ=1000 is used).

Signed-off-by: Thomas Renninger <trenn@suse.de>
Cc: Pallipadi Venkatesh <venkatesh.pallipadi@intel.com>
Signed-off-by: Dave Jones <davej@redhat.com>
2009-06-15 11:49:41 -04:00
..
cpufreq_conservative.c [CPUFREQ] ondemand: Uncouple minimal sampling rate from HZ in NO_HZ case 2009-06-15 11:49:41 -04:00
cpufreq_ondemand.c [CPUFREQ] ondemand: Uncouple minimal sampling rate from HZ in NO_HZ case 2009-06-15 11:49:41 -04:00
cpufreq_performance.c [CPUFREQ] Don't export governors for default governor 2008-10-09 13:52:44 -04:00
cpufreq_powersave.c [CPUFREQ] Don't export governors for default governor 2008-10-09 13:52:44 -04:00
cpufreq_stats.c [CPUFREQ] checkpatch cleanups for cpufreq_stats 2009-02-24 22:47:30 -05:00
cpufreq_userspace.c [CPUFREQ] checkpatch cleanups for userspace governor 2009-02-24 22:47:30 -05:00
cpufreq.c cpumask: alloc zeroed cpumask for static cpumask_var_ts 2009-06-09 22:30:27 +09:30
freq_table.c [CPUFREQ] checkpatch cleanups for freq_table 2009-02-24 22:47:30 -05:00
Kconfig trivial: fix an -> a typos in documentation and comments 2009-01-06 11:28:07 +01:00
Makefile [CPUFREQ] Conservative cpufreq governer 2005-05-31 19:03:47 -07:00