# git rev-parse -q --verify 2accfdb7eff65f390c4308b0e9cb7c3fe48ad63c^{commit} 2accfdb7eff65f390c4308b0e9cb7c3fe48ad63c already have revision, skipping fetch # git checkout -q -f -B kisskb 2accfdb7eff65f390c4308b0e9cb7c3fe48ad63c # git clean -qxdf # < git log -1 # commit 2accfdb7eff65f390c4308b0e9cb7c3fe48ad63c # Author: Linus Torvalds # Date: Mon Jul 29 10:58:28 2024 -0700 # # profiling: attempt to remove per-cpu profile flip buffer # # This is the really old legacy kernel profiling code, which has long # since been obviated by "real profiling" (ie 'prof' and company), and # mainly remains as a source of syzbot reports. # # There are anecdotal reports that people still use it for boot-time # profiling, but it's unlikely that such use would care about the old NUMA # optimizations in this code from 2004 (commit ad02973d42: "profile: 512x # Altix timer interrupt livelock fix" in the BK import archive at [1]) # # So in order to head off future syzbot reports, let's try to simplify # this code and get rid of the per-cpu profile buffers that are quite a # large portion of the complexity footprint of this thing (including CPU # hotplug callbacks etc). # # It's unlikely anybody will actually notice, or possibly, as Thomas put # it: "Only people who indulge in nostalgia will notice :)". # # That said, if it turns out that this code is actually actively used by # somebody, we can always revert this removal. Thus the "attempt" in the # summary line. # # [ Note: in a small nod to "the profiling code can cause NUMA problems", # this also removes the "increment the last entry in the profiling array # on any unknown hits" logic. That would account any program counter in # a module to that single counter location, and might exacerbate any # NUMA cacheline bouncing issues ] # # Link: https://lore.kernel.org/all/CAHk-=wgs52BxT4Zjmjz8aNvHWKxf5_ThBY4bYL1Y6CTaNL2dTw@mail.gmail.com/ # Link: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git [1] # Cc: Thomas Gleixner # Cc: Tetsuo Handa # Signed-off-by: Linus Torvalds # < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-gcc --version # < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld --version # < git log --format=%s --max-count=1 2accfdb7eff65f390c4308b0e9cb7c3fe48ad63c # make -s -j 40 ARCH=powerpc O=/kisskb/build/linus_corenet64_smp_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- corenet64_smp_defconfig Using /kisskb/src/arch/powerpc/configs/corenet_base.config as base Merging /kisskb/src/arch/powerpc/configs/85xx-64bit.config Merging /kisskb/src/arch/powerpc/configs/85xx-smp.config Merging /kisskb/src/arch/powerpc/configs/altivec.config Merging /kisskb/src/arch/powerpc/configs/85xx-hw.config Merging /kisskb/src/arch/powerpc/configs/fsl-emb-nonhw.config Merging /kisskb/src/arch/powerpc/configs/dpaa.config # # merged configuration written to .config (needs make) # # < make -s -j 40 ARCH=powerpc O=/kisskb/build/linus_corenet64_smp_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- help # make -s -j 40 ARCH=powerpc O=/kisskb/build/linus_corenet64_smp_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- olddefconfig # make -s -j 40 ARCH=powerpc O=/kisskb/build/linus_corenet64_smp_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- Completed OK # rm -rf /kisskb/build/linus_corenet64_smp_defconfig_powerpc-gcc5 # Build took: 0:01:25.367430