# git rev-parse -q --verify de8a34242c88473ee615f66a7ded095f094e708e^{commit}
de8a34242c88473ee615f66a7ded095f094e708e
already have revision, skipping fetch
# git checkout -q -f -B kisskb de8a34242c88473ee615f66a7ded095f094e708e
# git clean -qxdf
# < git log -1
# commit de8a34242c88473ee615f66a7ded095f094e708e
# Author: Nicholas Piggin <npiggin@gmail.com>
# Date:   Thu Jul 9 17:07:59 2020 +1000
# 
#     lazy tlb: shoot lazies, a non-refcounting lazy tlb option
#     
#     On big systems, the mm refcount can become highly contented when doing
#     a lot of context switching with threaded applications (particularly
#     switching between the idle thread and an application thread).
#     
#     Abandoning lazy tlb slows switching down quite a bit in the important
#     user->idle->user cases, so so instead implement a non-refcounted scheme
#     that causes __mmdrop() to IPI all CPUs in the mm_cpumask and shoot down
#     any remaining lazy ones.
#     
#     On a 16-socket 192-core POWER8 system, a context switching benchmark
#     with as many software threads as CPUs (so each switch will go in and
#     out of idle), upstream can achieve a rate of about 1 million context
#     switches per second. After this patch it goes up to 118 million.
#     
#     Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
# < /opt/cross/kisskb/korg/gcc-4.9.4-nolibc/powerpc64-linux/bin/powerpc64-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-4.9.4-nolibc/powerpc64-linux/bin/powerpc64-linux-ld --version
# < git log --format=%s --max-count=1 de8a34242c88473ee615f66a7ded095f094e708e
# < make -s -j 80 ARCH=powerpc O=/kisskb/build/npiggin_ppc64_defconfig_powerpc-gcc4.9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-4.9.4-nolibc/powerpc64-linux/bin/powerpc64-linux-  ppc64_defconfig
# < make -s -j 80 ARCH=powerpc O=/kisskb/build/npiggin_ppc64_defconfig_powerpc-gcc4.9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-4.9.4-nolibc/powerpc64-linux/bin/powerpc64-linux-  help
# make -s -j 80 ARCH=powerpc O=/kisskb/build/npiggin_ppc64_defconfig_powerpc-gcc4.9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-4.9.4-nolibc/powerpc64-linux/bin/powerpc64-linux-  olddefconfig
# make -s -j 80 ARCH=powerpc O=/kisskb/build/npiggin_ppc64_defconfig_powerpc-gcc4.9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-4.9.4-nolibc/powerpc64-linux/bin/powerpc64-linux-  
Completed OK
# rm -rf /kisskb/build/npiggin_ppc64_defconfig_powerpc-gcc4.9
# Build took: 0:03:28.221305