[v3,0/3] arm64/fpsimd: Don't disable softirq when touching FPSIMD/SVE state

Message

Julien Grall April 23, 2019, 1:57 p.m. UTC

Hi all,

This patch series keeps softirqs enabled while touching FPSIMD/SVE state.
For more details on the impact see patch #3.

This patch series has been benchmarked on Linux 5.1-rc4 with defconfig.

On Juno2:
    * hackbench 100 process 1000 (10 times)
    * .7% quicker

On ThunderX 2:
    * hackbench 1000 process 1000 (20 times)
    * 3.4% quicker

Note that while the benchmark has been done on 5.1-rc4, the patch series is
based on kvm-arm/next as it has few conflicts with the
SVE KVM series.

Cheers,

Julien Grall (3):
  arm64/fpsimd: Remove the prototype for sve_flush_cpu_state()
  arch/arm64: fpsimd: Introduce fpsimd_save_and_flush_cpu_state() and
    use it
  arm64/fpsimd: Don't disable softirq when touching FPSIMD/SVE state

 arch/arm64/include/asm/fpsimd.h |   6 +-
 arch/arm64/include/asm/simd.h   |  10 +--
 arch/arm64/kernel/fpsimd.c      | 135 +++++++++++++++++++++++++++-------------
 arch/arm64/kvm/fpsimd.c         |   4 +-
 4 files changed, 100 insertions(+), 55 deletions(-)