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  1. Nov 15, 2012
  3. Oct 18, 2012
    • Deepthi Dharwar's avatar
      cpuidle/powerpc: Fix snooze state problem in the cpuidle design on pseries. · 83dac594
      Deepthi Dharwar authored 
      

Earlier without cpuidle framework on pseries, the native arch
idle routine comprised of both snooze and nap
states.  smt_snooze_delay variable was used to delay
the idle process entry to deeper idle state like  nap.
With the coming of cpuidle, this arch specific idle was replaced
by two different idle routines, one for supporting snooze and other
for nap. This enabled addition of more
low level idle states on pseries in the future.

On adopting the generic cpuidle framework for POWER systems,
the decision of which idle state to choose from,  given a predicted
idle time is taken by the menu governor based on
target_residency and  exit_latency of the idle states.
target_residency is the minimum time to be resident in that idle state.
Exit_latency is time taken to exit out of idle state.
Deeper the idle state, both the target residency and exit latency
would be higher.

In the current design, smt_snooze_delay is used as target_residency
for the  snooze state which is incorrect, as it is not the
minimum but the maximum duration to be in snooze state.
This would  result in the governor in taking bad decision,
as presently target_residency of nap < target_residency of snooze
inspite of nap being deeper idle state.

This patch aims to fix this problem by replacing the smt_snooze_delay loop
in snooze state, with the need_resched()  as the governor is aware of
entry and exit of various idle transitions based on which
next idle time prediction.

The governor is intelligent enough to determine the idle state the needs to
be transitioned to and maintains a whole of heuristics including
io load, previous idle states predictions etc for the same, based on
which idle state entry decision is taken.

With this fix, of setting target_residency of snooze to 0
					     nap to smt_snooze_delay
if the predicted idle time is less
than smt_snooze_delay (target_residency of nap)
value governor would pick snooze state, else nap. This adhers to the
previous native idle design.

Signed-off-by: default avatarDeepthi Dharwar <deepthi@linux.vnet.ibm.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      83dac594
    • Deepthi Dharwar's avatar
      cpuidle/powerpc: Fix smt_snooze_delay functionality. · 8ea959a1
      Deepthi Dharwar authored 
      smt_snooze_delay was designed to  delay idle loop's nap entry
in the native idle code before it got  ported over to use as part of
the cpuidle framework.

A -ve value  assigned to smt_snooze_delay should result in
busy looping, in other words disabling the entry to nap state.

	- https://lists.ozlabs.org/pipermail/linuxppc-dev/2010-May/082450.html



This particular functionality can be achieved currently by
echo 1 > /sys/devices/system/cpu/cpu*/state1/disable
but it is broken when one assigns -ve value to  the smt_snooze_delay
variable either via sysfs entry or ppc64_cpu util.

This patch aims to fix this, by disabling nap state when smt_snooze_delay
variable is set to -ve value.

Signed-off-by: default avatarDeepthi Dharwar <deepthi@linux.vnet.ibm.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      8ea959a1
    • Deepthi Dharwar's avatar
      cpuidle/powerpc: Fix target residency initialisation in pseries cpuidle · 817deb05
      Deepthi Dharwar authored 
      

Remove the redundant target residency initialisation in pseries_cpuidle_driver_init().
This is currently over-writing the residency time updated as part of the static
table, resulting in  all the idle states having the same target
residency of 100us which is incorrect. This may result in the menu governor making
wrong state decisions.

Signed-off-by: default avatarDeepthi Dharwar <deepthi@linux.vnet.ibm.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      817deb05
    • Aneesh Kumar K.V's avatar
      powerpc: Build fix for powerpc KVM · ce236ab5
      Aneesh Kumar K.V authored 
      

Fix build failure for powerpc KVM by adding missing VPN_SHIFT definition
and the ';'

arch/powerpc/kvm/book3s_32_mmu_host.c: In function 'kvmppc_mmu_map_page':
arch/powerpc/kvm/book3s_32_mmu_host.c:176: error: 'VPN_SHIFT' undeclared (first use in this function)
arch/powerpc/kvm/book3s_32_mmu_host.c:176: error: (Each undeclared identifier is reported only once
arch/powerpc/kvm/book3s_32_mmu_host.c:176: error: for each function it appears in.)
arch/powerpc/kvm/book3s_32_mmu_host.c:178: error: expected ';' before 'next_pteg'
arch/powerpc/kvm/book3s_32_mmu_host.c:190: error: label 'next_pteg' used but not defined
make[1]: *** [arch/powerpc/kvm/book3s_32_mmu_host.o] Error 1

Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      ce236ab5
    • Benjamin Herrenschmidt's avatar
      Revert "powerpc/perf: Use pmc_overflow() to detect rolled back events" · 72523d80
      Benjamin Herrenschmidt authored 
      This reverts commit 81331211.

This revert was requested by the author of the patch as it seems
to cause system hangs with some low frequency events
      72523d80
    • Linus Torvalds's avatar
      Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net · 18673533
      Linus Torvalds authored 
      Pull networking fixes from David Miller:

 1) Fix regression in /proc/net/if_inet6, sometimes devices do not get
    listed.  From Eric Dumazet.

 2) Add IPSEC networking sub-section to MAINTAINERS.

 3) S390 networking fixes from Hendrik Brueckner and Stefan Raspl.

 4) Fix enslavement of devices that can't do VLAN properly, from Jiri
    Pirko.

 5) SCTP sack handling fix from Zijie Pan.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net:
  ipv6: addrconf: fix /proc/net/if_inet6
  bnx2x: fix handling mf storage modes
  qeth: fix deadlock between recovery and bonding driver
  smsgiucv: reestablish IUCV path after resume
  sctp: fix call to SCTP_CMD_PROCESS_SACK in sctp_cmd_interpreter()
  vlan: fix bond/team enslave of vlan challenged slave/port
  MAINTAINERS: Add explicit section for IPSEC networking.
      18673533
    • Linus Torvalds's avatar
      Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc · ccbfddb7
      Linus Torvalds authored 
      Pull sparc fixes from David Miller:
 "Two sparc64 perf bug fixes and add a sysrq facility so I can diagnose
  these kinds of problems more quickly in the future."

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc:
  sparc64: Fix bit twiddling in sparc_pmu_enable_event().
  sparc64: Add global PMU register dumping via sysrq.
  sparc64: Like x86 we should check current->mm during perf backtrace generation.
      ccbfddb7
  5. Oct 17, 2012