This patchset enables the usage of haltpoll governer on arm64. This is
specifically interesting for KVM guests by reducing the IPC latencies.
Here are some benchmarks without/with haltpoll for a KVM guest:
a) without haltpoll:
perf bench sched pipe
# Running 'sched/pipe' benchmark:
# Executed 1000000 pipe operations between two processes
Total time: 8.138 [sec]
8.138094 usecs/op
122878 ops/sec
b) with haltpoll:
perf bench sched pipe
# Running 'sched/pipe' benchmark:
# Executed 1000000 pipe operations between two processes
Total time: 5.003 [sec]
5.003085 usecs/op
199876 ops/sec
v4 changes from v3:
- change 7/8 per Rafael input: drop the parens and use ret for the final check
- add 8/8 which renames the guard for building poll_state
v3 changes from v2:
- fix 1/7 per Petr Mladek - remove ARCH_HAS_CPU_RELAX from arch/x86/Kconfig
- add Ack-by from Rafael Wysocki on 2/7
v2 changes from v1:
- added patch 7 where we change cpu_relax with smp_cond_load_relaxed per PeterZ
(this improves by 50% at least the CPU cycles consumed in the tests above:
10,716,881,137 now vs 14,503,014,257 before)
- removed the ifdef from patch 1 per RafaelW
Joao Martins (6):
x86: Move ARCH_HAS_CPU_RELAX to arch
x86/kvm: Move haltpoll_want() to be arch defined
governors/haltpoll: Drop kvm_para_available() check
arm64: Select ARCH_HAS_CPU_RELAX
arm64: Define TIF_POLLING_NRFLAG
cpuidle-haltpoll: ARM64 support
Mihai Carabas (2):
cpuidle/poll_state: replace cpu_relax with smp_cond_load_relaxed
cpuidle: replace with HAS_CPU_RELAX with HAS_WANTS_IDLE_POLL
arch/Kconfig | 3 +++
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/thread_info.h | 6 ++++++
arch/x86/Kconfig | 4 +---
arch/x86/include/asm/cpuidle_haltpoll.h | 1 +
arch/x86/kernel/kvm.c | 10 ++++++++++
drivers/acpi/processor_idle.c | 4 ++--
drivers/cpuidle/Kconfig | 4 ++--
drivers/cpuidle/Makefile | 2 +-
drivers/cpuidle/cpuidle-haltpoll.c | 8 ++------
drivers/cpuidle/governors/haltpoll.c | 5 +----
drivers/cpuidle/poll_state.c | 15 ++++++++++-----
include/linux/cpuidle.h | 2 +-
include/linux/cpuidle_haltpoll.h | 5 +++++
14 files changed, 46 insertions(+), 24 deletions(-)
--
1.8.3.1
