On 7/24/20 9:14 AM, Nicholas Piggin wrote:
Updated with everybody's feedback (thanks all), and more performance
results.
What I've found is I might have been measuring the worst load point for
the paravirt case, and by looking at a range of loads it's clear that
queued spinlocks are overall better even on PV, doubly so when you look
at the generally much improved worst case latencies.
I have defaulted it to N even though I'm less concerned about the PV
numbers now, just because I think it needs more stress testing. But
it's very nicely selectable so should be low risk to include.
All in all this is a very cool technology and great results especially
on the big systems but even on smaller ones there are nice gains. Thanks
Waiman and everyone who developed it.
Thanks,
Nick
Nicholas Piggin (6):
powerpc/pseries: move some PAPR paravirt functions to their own file
powerpc: move spinlock implementation to simple_spinlock
powerpc/64s: implement queued spinlocks and rwlocks
powerpc/pseries: implement paravirt qspinlocks for SPLPAR
powerpc/qspinlock: optimised atomic_try_cmpxchg_lock that adds the
lock hint
powerpc: implement smp_cond_load_relaxed
arch/powerpc/Kconfig | 15 +
arch/powerpc/include/asm/Kbuild | 1 +
arch/powerpc/include/asm/atomic.h | 28 ++
arch/powerpc/include/asm/barrier.h | 14 +
arch/powerpc/include/asm/paravirt.h | 87 +++++
arch/powerpc/include/asm/qspinlock.h | 91 ++++++
arch/powerpc/include/asm/qspinlock_paravirt.h | 7 +
arch/powerpc/include/asm/simple_spinlock.h | 288 ++++++++++++++++
.../include/asm/simple_spinlock_types.h | 21 ++
arch/powerpc/include/asm/spinlock.h | 308 +-----------------
arch/powerpc/include/asm/spinlock_types.h | 17 +-
arch/powerpc/lib/Makefile | 3 +
arch/powerpc/lib/locks.c | 12 +-
arch/powerpc/platforms/pseries/Kconfig | 9 +-
arch/powerpc/platforms/pseries/setup.c | 4 +-
include/asm-generic/qspinlock.h | 4 +
16 files changed, 588 insertions(+), 321 deletions(-)
create mode 100644 arch/powerpc/include/asm/paravirt.h
create mode 100644 arch/powerpc/include/asm/qspinlock.h
create mode 100644 arch/powerpc/include/asm/qspinlock_paravirt.h
create mode 100644 arch/powerpc/include/asm/simple_spinlock.h
create mode 100644 arch/powerpc/include/asm/simple_spinlock_types.h
That patch series looks good to me. Thanks for working on this.
For the series,
Acked-by: Waiman Long <longman@xxxxxxxxxx>
