# git rev-parse -q --verify de8a34242c88473ee615f66a7ded095f094e708e^{commit}
# git fetch -q -n -f git://gitlab.ozlabs.ibm.com/mirror/linux-npiggin.git kerkins
# git rev-parse -q --verify de8a34242c88473ee615f66a7ded095f094e708e^{commit}
de8a34242c88473ee615f66a7ded095f094e708e
# 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-11.1.0-nolibc/x86_64-linux/bin/x86_64-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-11.1.0-nolibc/x86_64-linux/bin/x86_64-linux-ld --version
# < git log --format=%s --max-count=1 de8a34242c88473ee615f66a7ded095f094e708e
# < make -s -j 48 ARCH=x86_64 O=/kisskb/build/npiggin_x86_64-allnoconfig_x86_64-gcc11 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-11.1.0-nolibc/x86_64-linux/bin/x86_64-linux-  allnoconfig
# < make -s -j 48 ARCH=x86_64 O=/kisskb/build/npiggin_x86_64-allnoconfig_x86_64-gcc11 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-11.1.0-nolibc/x86_64-linux/bin/x86_64-linux-  help
# make -s -j 48 ARCH=x86_64 O=/kisskb/build/npiggin_x86_64-allnoconfig_x86_64-gcc11 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-11.1.0-nolibc/x86_64-linux/bin/x86_64-linux-  olddefconfig
# make -s -j 48 ARCH=x86_64 O=/kisskb/build/npiggin_x86_64-allnoconfig_x86_64-gcc11 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-11.1.0-nolibc/x86_64-linux/bin/x86_64-linux-  
arch/x86/entry/thunk_64.o: warning: objtool: missing symbol table
make[3]: *** [/kisskb/src/scripts/Makefile.build:361: arch/x86/entry/thunk_64.o] Error 1
make[3]: *** Deleting file 'arch/x86/entry/thunk_64.o'
make[3]: *** Waiting for unfinished jobs....
make[2]: *** [/kisskb/src/scripts/Makefile.build:497: arch/x86/entry] Error 2
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [/kisskb/src/Makefile:1756: arch/x86] Error 2
make[1]: *** Waiting for unfinished jobs....
make: *** [Makefile:185: __sub-make] Error 2
Command 'make -s -j 48 ARCH=x86_64 O=/kisskb/build/npiggin_x86_64-allnoconfig_x86_64-gcc11 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-11.1.0-nolibc/x86_64-linux/bin/x86_64-linux-  ' returned non-zero exit status 2
# rm -rf /kisskb/build/npiggin_x86_64-allnoconfig_x86_64-gcc11
# Build took: 0:00:38.719529