d63b8524 - kbuild: Fix Propeller build option

Fri, 08 Nov 2024 21:49:53 +0000

kbuild: Fix Propeller build optionThe '-fbasic-block-sections=labels' option has been deprecated in tipof tree clang (20.0.0) [1]. While the option still works, a warning isemitted: clang: warning: argument '-fbasic-block-sections=labels' is deprecated, use '-fbasic-block-address-map' instead [-Wdeprecated]Add a version check to set the proper option.Link: https://github.com/llvm/llvm-project/pull/110039 [1]Signed-off-by: Rong Xu Reported-by: Nathan Chancellor Suggested-by: Nathan Chancellor Reviewed-by: Nathan Chancellor Tested-by: Nathan Chancellor Signed-off-by: Masahiro Yamada List of files: /linux-6.15/scripts/Makefile.propeller

d5dc9583 - kbuild: Add Propeller configuration for kernel build

Sat, 02 Nov 2024 17:51:14 +0000

kbuild: Add Propeller configuration for kernel buildAdd the build support for using Clang's Propeller optimizer. LikeAutoFDO, Propeller uses hardware sampling to gather informationabout the frequency of execution of different code paths within abinary. This information is then used to guide the compiler'soptimization decisions, resulting in a more efficient binary.The support requires a Clang compiler LLVM 19 or later, and thecreate_llvm_prof tool(https://github.com/google/autofdo/releases/tag/v0.30.1). Thiscommit is limited to x86 platforms that support PMU featureslike LBR on Intel machines and AMD Zen3 BRS.Here is an example workflow for building an AutoFDO+Propelleroptimized 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=“” is the profile collected when doing a non-PropellerAutoFDO build. This step builds a kernel that has the same optimizationlevel as AutoFDO, plus a metadata section that records basic blockinformation. This kernel image runs as fast as an AutoFDO optimizedkernel.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 \ -o -- 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 -o -- 4) (Optional) Download the raw perf file to the host machine.5) Generate Propeller profile: $ create_llvm_prof --binary= --profile= \ --format=propeller --propeller_output_module_name \ --out=_cc_profile.txt \ --propeller_symorder=_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). "" can be something like "/home/user/dir/any_string". This command generates a pair of Propeller profiles: "_cc_profile.txt" and "_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= \ CLANG_PROPELLER_PROFILE_PREFIX=Co-developed-by: Han Shen Signed-off-by: Han Shen Signed-off-by: Rong Xu Suggested-by: Sriraman Tallam Suggested-by: Krzysztof Pszeniczny Suggested-by: Nick Desaulniers Suggested-by: Stephane Eranian Tested-by: Yonghong Song Tested-by: Nathan Chancellor Reviewed-by: Kees Cook Signed-off-by: Masahiro Yamada List of files: /linux-6.15/scripts/Makefile.propeller

Changes in Makefile.propeller

d63b8524 - kbuild: Fix Propeller build option

d5dc9583 - kbuild: Add Propeller configuration for kernel build