idle performance improvements

I rebased this on the powerpc next tree.

A couple of things are changed since last post:

- Patch 1 now properly accounts for the fact the powernv idle wakeups do not re-enable interrupts until the cpuidle driver enables them. This was not quite right in the previous patch (and prep_irq_for_idle() is not quite right for that case so a new primitive has to be introduced).

- Patch to replace interrupts from system reset wakeup changed rather than replaying directly, it just marks the IRQ in the lazy pending bit and it will get replayed at the right time when irqs are re-enabled.

Thanks,
Nick

Nicholas Piggin (14):
powerpc/64s: idle move soft interrupt mask logic into C code powerpc/64s: idle hotplug lazy-irq simplification powerpc/64s: idle provide a default idle for POWER9 powerpc/64s: idle process interrupts from system reset wakeup powerpc/64s: msgclr when handling doorbell exceptions powerpc/64s: interrupt replay balance the return branch predictor powerpc/64s: idle branch to handler with virtual mode offset powerpc/64s: idle avoid SRR usage in idle sleep/wake paths powerpc/64s: idle hmi wakeup is unlikely
powerpc/64s: cpuidle set polling before enabling irqs powerpc/64s: cpuidle read mostly for common globals powerpc/64s: cpuidle no memory barrier after break from idle powerpc/64: runlatch CTRL[RUN] set optimisation powerpc/64s: idle runlatch switch is done with MSR[EE]=0

 arch/powerpc/include/asm/dbell.h         |  13 +++
 arch/powerpc/include/asm/exception-64s.h |  17 +++-
 arch/powerpc/include/asm/hw_irq.h        |   5 ++
 arch/powerpc/include/asm/machdep.h       |   1 +
 arch/powerpc/include/asm/ppc-opcode.h    |   3 +
 arch/powerpc/include/asm/processor.h     |  10 +--
 arch/powerpc/kernel/asm-offsets.c        |   1 +
 arch/powerpc/kernel/exceptions-64s.S     |  33 ++++++--
 arch/powerpc/kernel/idle_book3s.S        | 135 +++++++++----------------------
 arch/powerpc/kernel/irq.c                |  58 ++++++++++++-
 arch/powerpc/kernel/process.c            |  12 +--
 arch/powerpc/kvm/book3s_hv_rmhandlers.S  |   8 +-
 arch/powerpc/platforms/powernv/idle.c    |  90 +++++++++++++++++++--
 arch/powerpc/platforms/powernv/smp.c     |  31 ++++---
 arch/powerpc/platforms/powernv/subcore.c |   3 +-
 drivers/cpuidle/cpuidle-powernv.c        |  37 +++++----
 drivers/cpuidle/cpuidle-pseries.c        |  22 +++--
 17 files changed, 309 insertions(+), 170 deletions(-)

2.11.0

What do you mean ? We shouldn't be going to sleep with the CPU thinking it's interrupts are off, otherwise we end up effectively "taking an interrupt while off" which is not right and it will cause accounting to think we are off for too long.

Is this a generic cpuidle problem or a powerpc issue ?

I'd rather we don't have to of those "prep_for_idle...". If necessary sync the other one.

cpuidle drivers enter their idle state with local_irq_disable(). powernv cpuidle driver currently does not call trace_hardirqs_on() before going to sleep (e.g., it does not use prep_irq_for_idle()).

I did a previous patch that uses prep_irq_for_idle directly, but that assumes when we return from idle that local irqs should be on. The generic cpuidle does not want that, I haven't dug into exactly why not. But it seems to work better just to put the SRR1 wakeup reason into the irq_pending bit and let the lazy irq logic take care of the rest.

Okay one can call the other rather than implementing twice.

Thanks,
Nick