# git rev-parse -q --verify d909f9109c301f4e9e41678025c45d719ab8f7d7^{commit}
d909f9109c301f4e9e41678025c45d719ab8f7d7
already have revision, skipping fetch
# git checkout -q -f -B kisskb d909f9109c301f4e9e41678025c45d719ab8f7d7
# git clean -qxdf
# < git log -1
# commit d909f9109c301f4e9e41678025c45d719ab8f7d7
# Author: Nicholas Piggin <npiggin@gmail.com>
# Date:   Mon Jun 10 13:08:18 2019 +1000
# 
#     powerpc/64s/radix: Enable HAVE_ARCH_HUGE_VMAP
#     
#     This sets the HAVE_ARCH_HUGE_VMAP option, and defines the required
#     page table functions.
#     
#     This enables huge (2MB and 1GB) ioremap mappings. I don't have a
#     benchmark for this change, but huge vmap will be used by a later core
#     kernel change to enable huge vmalloc memory mappings. This improves
#     cached `git diff` performance by about 5% on a 2-node POWER9 with 32MB
#     size dentry cache hash.
#     
#       Profiling git diff dTLB misses with a vanilla kernel:
#     
#       81.75%  git      [kernel.vmlinux]    [k] __d_lookup_rcu
#        7.21%  git      [kernel.vmlinux]    [k] strncpy_from_user
#        1.77%  git      [kernel.vmlinux]    [k] find_get_entry
#        1.59%  git      [kernel.vmlinux]    [k] kmem_cache_free
#     
#                 40,168      dTLB-miss
#            0.100342754 seconds time elapsed
#     
#       With powerpc huge vmalloc:
#     
#                  2,987      dTLB-miss
#            0.095933138 seconds time elapsed
#     
#     Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
# < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/s390-linux/bin/s390-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/s390-linux/bin/s390-linux-ld --version
# < git log --format=%s --max-count=1 d909f9109c301f4e9e41678025c45d719ab8f7d7
# < make -s -j 24 ARCH=s390 O=/kisskb/build/powerpc-next_s390-defconfig_s390x-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/s390-linux/bin/s390-linux-  defconfig
# make -s -j 24 ARCH=s390 O=/kisskb/build/powerpc-next_s390-defconfig_s390x-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/s390-linux/bin/s390-linux-  
arch/s390/../../virt/kvm/kvm_main.o: In function `kvm_vcpu_unmap':
/kisskb/src/arch/s390/kvm/../../../virt/kvm/kvm_main.c:1799: undefined reference to `memunmap'
make[1]: *** [/kisskb/src/Makefile:1052: vmlinux] Error 1
make: *** [Makefile:179: sub-make] Error 2
Command 'make -s -j 24 ARCH=s390 O=/kisskb/build/powerpc-next_s390-defconfig_s390x-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/s390-linux/bin/s390-linux-  ' returned non-zero exit status 2
# rm -rf /kisskb/build/powerpc-next_s390-defconfig_s390x-gcc8
# Build took: 0:02:15.620129