kernel_optimize_test/include
Ai Li 71abbbf856 cpuidle: extend cpuidle and menu governor to handle dynamic states
On some SoC chips, HW resources may be in use during any particular idle
period.  As a consequence, the cpuidle states that the SoC is safe to
enter can change from idle period to idle period.  In addition, the
latency and threshold of each cpuidle state can vary, depending on the
operating condition when the CPU becomes idle, e.g.  the current cpu
frequency, the current state of the HW blocks, etc.

cpuidle core and the menu governor, in the current form, are geared
towards cpuidle states that are static, i.e.  the availabiltiy of the
states, their latencies, their thresholds are non-changing during run
time.  cpuidle does not provide any hook that cpuidle drivers can use to
adjust those values on the fly for the current idle period before the menu
governor selects the target cpuidle state.

This patch extends cpuidle core and the menu governor to handle states
that are dynamic.  There are three additions in the patch and the patch
maintains backwards-compatibility with existing cpuidle drivers.

1) add prepare() to struct cpuidle_device.  A cpuidle driver can hook
   into the callback and cpuidle will call prepare() before calling the
   governor's select function.  The callback gives the cpuidle driver a
   chance to update the dynamic information of the cpuidle states for the
   current idle period, e.g.  state availability, latencies, thresholds,
   power values, etc.

2) add CPUIDLE_FLAG_IGNORE as one of the state flags.  In the prepare()
   function, a cpuidle driver can set/clear the flag to indicate to the
   menu governor whether a cpuidle state should be ignored, i.e.  not
   available, during the current idle period.

3) add power_specified bit to struct cpuidle_device.  The menu governor
   currently assumes that the cpuidle states are arranged in the order of
   increasing latency, threshold, and power savings.  This is true or can
   be made true for static states.  Once the state parameters are dynamic,
   the latencies, thresholds, and power savings for the cpuidle states can
   increase or decrease by different amounts from idle period to idle
   period.  So the assumption of increasing latency, threshold, and power
   savings from Cn to C(n+1) can no longer be guaranteed.

It can be straightforward to calculate the power consumption of each
available state and to specify it in power_usage for the idle period.
Using the power_usage fields, the menu governor then selects the state
that has the lowest power consumption and that still satisfies all other
critieria.  The power_specified bit defaults to 0.  For existing cpuidle
drivers, cpuidle detects that power_specified is 0 and fills in a dummy
set of power_usage values.

Signed-off-by: Ai Li <aili@codeaurora.org>
Cc: Len Brown <len.brown@intel.com>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-08-09 20:45:04 -07:00
..
acpi Merge branch 'acpica' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6 2010-08-07 17:08:30 -07:00
asm-generic topology: alternate fix for ia64 tiger_defconfig build breakage 2010-08-09 20:44:57 -07:00
crypto
drm Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 2010-08-07 12:42:58 -07:00
keys DNS: Separate out CIFS DNS Resolver code 2010-08-05 17:17:51 +00:00
linux cpuidle: extend cpuidle and menu governor to handle dynamic states 2010-08-09 20:45:04 -07:00
math-emu
media V4L/DVB: dib0700: break keytable into NEC and RC-5 variants 2010-08-02 16:43:49 -03:00
mtd
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6 2010-08-04 11:47:58 -07:00
pcmcia pcmcia: use struct resource for PCMCIA devices, part 2 2010-08-03 09:04:16 +02:00
rdma IB: Rename RAW_ETY to RAW_ETHERTYPE 2010-08-04 10:44:19 -07:00
rxrpc
scsi [SCSI] implement runtime Power Management 2010-07-28 09:07:50 -05:00
sound Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6 2010-08-07 17:07:31 -07:00
trace memcg: add mm_vmscan_memcg_isolate tracepoint 2010-08-09 20:45:03 -07:00
video
xen
Kbuild