The patch of Jan Glauber enables queued spinlocks on arm64. I rebased it on
latest kernel sources, and added a couple of fixes to headers to apply it
smoothly.
Though, locktourture test shows significant performance degradation in the
acquisition of rw-lock for read on qemu:
Before After
spin_lock-torture: 38957034 37076367 -4.83
rw_lock-torture W: 5369471 18971957 253.33
rw_lock-torture R: 6413179 3668160 -42.80
I'm not much experienced in locking, and so wonder how it's possible that
simple switching to generic queued rw-lock causes so significant performance
degradation, while in theory it should improve it. Even more, on x86 there
are no such problems probably.
I also think that patches 1 and 2 are correct and useful, and should be applied
anyway.
Any comments appreciated.
Yury.
Jan Glauber (1):
arm64/locking: qspinlocks and qrwlocks support
Yury Norov (2):
kernel/locking: #include <asm/spinlock.h> in qrwlock.c
asm-generic: don't #include <linux/atomic.h> in qspinlock_types.h
arch/arm64/Kconfig | 2 ++
arch/arm64/include/asm/qrwlock.h | 7 +++++++
arch/arm64/include/asm/qspinlock.h | 20 ++++++++++++++++++++
arch/arm64/include/asm/spinlock.h | 12 ++++++++++++
arch/arm64/include/asm/spinlock_types.h | 14 +++++++++++---
include/asm-generic/qspinlock.h | 1 +
include/asm-generic/qspinlock_types.h | 8 --------
kernel/locking/qrwlock.c | 1 +
8 files changed, 54 insertions(+), 11 deletions(-)
create mode 100644 arch/arm64/include/asm/qrwlock.h
create mode 100644 arch/arm64/include/asm/qspinlock.h
--
2.7.4
