# git rev-parse -q --verify 0dcc2d1066150787017a71f035145c566597dec7^{commit}
0dcc2d1066150787017a71f035145c566597dec7
already have revision, skipping fetch
# git checkout -q -f -B kisskb 0dcc2d1066150787017a71f035145c566597dec7
# git clean -qxdf
# < git log -1
# commit 0dcc2d1066150787017a71f035145c566597dec7
# Author: Rong Xu <xur@google.com>
# Date:   Sat Nov 2 10:51:14 2024 -0700
# 
#     kbuild: Add Propeller configuration for kernel build
#     
#     Add the build support for using Clang's Propeller optimizer. Like
#     AutoFDO, Propeller uses hardware sampling to gather information
#     about the frequency of execution of different code paths within a
#     binary. This information is then used to guide the compiler's
#     optimization decisions, resulting in a more efficient binary.
#     
#     The support requires a Clang compiler LLVM 19 or later, and the
#     create_llvm_prof tool
#     (https://github.com/google/autofdo/releases/tag/v0.30.1). This
#     commit is limited to x86 platforms that support PMU features
#     like LBR on Intel machines and AMD Zen3 BRS.
#     
#     Here is an example workflow for building an AutoFDO+Propeller
#     optimized kernel:
#     
#     1) Build the kernel on the host machine, with AutoFDO and Propeller
#        build config
#           CONFIG_AUTOFDO_CLANG=y
#           CONFIG_PROPELLER_CLANG=y
#        then
#           $ make LLVM=1 CLANG_AUTOFDO_PROFILE=<autofdo_profile>
#     
#     “<autofdo_profile>” is the profile collected when doing a non-Propeller
#     AutoFDO build. This step builds a kernel that has the same optimization
#     level as AutoFDO, plus a metadata section that records basic block
#     information. This kernel image runs as fast as an AutoFDO optimized
#     kernel.
#     
#     2) Install the kernel on test/production machines.
#     
#     3) Run the load tests. The '-c' option in perf specifies the sample
#        event period. We suggest using a suitable prime number,
#        like 500009, for this purpose.
#        For Intel platforms:
#           $ perf record -e BR_INST_RETIRED.NEAR_TAKEN:k -a -N -b -c <count> \
#             -o <perf_file> -- <loadtest>
#        For AMD platforms:
#           The supported system are: Zen3 with BRS, or Zen4 with amd_lbr_v2
#           # To see if Zen3 support LBR:
#           $ cat proc/cpuinfo | grep " brs"
#           # To see if Zen4 support LBR:
#           $ cat proc/cpuinfo | grep amd_lbr_v2
#           # If the result is yes, then collect the profile using:
#           $ perf record --pfm-events RETIRED_TAKEN_BRANCH_INSTRUCTIONS:k -a \
#             -N -b -c <count> -o <perf_file> -- <loadtest>
#     
#     4) (Optional) Download the raw perf file to the host machine.
#     
#     5) Generate Propeller profile:
#        $ create_llvm_prof --binary=<vmlinux> --profile=<perf_file> \
#          --format=propeller --propeller_output_module_name \
#          --out=<propeller_profile_prefix>_cc_profile.txt \
#          --propeller_symorder=<propeller_profile_prefix>_ld_profile.txt
#     
#        “create_llvm_prof” is the profile conversion tool, and a prebuilt
#        binary for linux can be found on
#        https://github.com/google/autofdo/releases/tag/v0.30.1 (can also build
#        from source).
#     
#        "<propeller_profile_prefix>" can be something like
#        "/home/user/dir/any_string".
#     
#        This command generates a pair of Propeller profiles:
#        "<propeller_profile_prefix>_cc_profile.txt" and
#        "<propeller_profile_prefix>_ld_profile.txt".
#     
#     6) Rebuild the kernel using the AutoFDO and Propeller profile files.
#           CONFIG_AUTOFDO_CLANG=y
#           CONFIG_PROPELLER_CLANG=y
#        and
#           $ make LLVM=1 CLANG_AUTOFDO_PROFILE=<autofdo_profile> \
#             CLANG_PROPELLER_PROFILE_PREFIX=<propeller_profile_prefix>
#     
#     Co-developed-by: Han Shen <shenhan@google.com>
#     Signed-off-by: Han Shen <shenhan@google.com>
#     Signed-off-by: Rong Xu <xur@google.com>
#     Suggested-by: Sriraman Tallam <tmsriram@google.com>
#     Suggested-by: Krzysztof Pszeniczny <kpszeniczny@google.com>
#     Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
#     Suggested-by: Stephane Eranian <eranian@google.com>
#     Tested-by: Yonghong Song <yonghong.song@linux.dev>
#     Tested-by: Nathan Chancellor <nathan@kernel.org>
#     Reviewed-by: Kees Cook <kees@kernel.org>
#     Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
# < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/x86_64-linux/bin/x86_64-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/x86_64-linux/bin/x86_64-linux-ld --version
# < git log --format=%s --max-count=1 0dcc2d1066150787017a71f035145c566597dec7
# make -s -j 160 ARCH=x86_64 O=/kisskb/build/kbuild_defconfig_x86_64-gcc8.1 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/x86_64-linux/bin/x86_64-linux-  defconfig
# < make -s -j 160 ARCH=x86_64 O=/kisskb/build/kbuild_defconfig_x86_64-gcc8.1 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/x86_64-linux/bin/x86_64-linux-  help
# make -s -j 160 ARCH=x86_64 O=/kisskb/build/kbuild_defconfig_x86_64-gcc8.1 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/x86_64-linux/bin/x86_64-linux-  olddefconfig
# make -s -j 160 ARCH=x86_64 O=/kisskb/build/kbuild_defconfig_x86_64-gcc8.1 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/x86_64-linux/bin/x86_64-linux-  
Completed OK
# rm -rf /kisskb/build/kbuild_defconfig_x86_64-gcc8.1
# Build took: 0:04:49.078639