# git rev-parse -q --verify 4df910620bebb5cfe234af16ac8f6474b60215fd^{commit} 4df910620bebb5cfe234af16ac8f6474b60215fd already have revision, skipping fetch # git checkout -q -f -B kisskb 4df910620bebb5cfe234af16ac8f6474b60215fd # git clean -qxdf # < git log -1 # commit 4df910620bebb5cfe234af16ac8f6474b60215fd # Author: Feng Tang # Date: Wed Nov 25 13:22:21 2020 +0800 # # mm: memcg: relayout structure mem_cgroup to avoid cache interference # # 0day reported one -22.7% regression for will-it-scale page_fault2 # case [1] on a 4 sockets 144 CPU platform, and bisected to it to be # caused by Waiman's optimization (commit bd0b230fe1) of saving one # 'struct page_counter' space for 'struct mem_cgroup'. # # Initially we thought it was due to the cache alignment change introduced # by the patch, but further debug shows that it is due to some hot data # members ('vmstats_local', 'vmstats_percpu', 'vmstats') sit in 2 adjacent # cacheline (2N and 2N+1 cacheline), and when adjacent cache line prefetch # is enabled, it triggers an "extended level" of cache false sharing for # 2 adjacent cache lines. # # So exchange the 2 member blocks, while keeping mostly the original # cache alignment, which can restore and even enhance the performance, # and save 64 bytes of space for 'struct mem_cgroup' (from 2880 to 2816, # with 0day's default RHEL-8.3 kernel config) # # [1]. https://lore.kernel.org/lkml/20201102091543.GM31092@shao2-debian/ # # Fixes: bd0b230fe145 ("mm/memcg: unify swap and memsw page counters") # Reported-by: kernel test robot # Signed-off-by: Feng Tang # Acked-by: Waiman Long # Signed-off-by: Linus Torvalds # < /opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux-gcc --version # < /opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux-ld --version # < git log --format=%s --max-count=1 4df910620bebb5cfe234af16ac8f6474b60215fd # < make -s -j 80 ARCH=um O=/kisskb/build/linus_um-allyesconfig_um-x86_64 CROSS_COMPILE=/opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux- SUBARCH=x86_64 allyesconfig WARNING: unmet direct dependencies detected for MFD_CORE Depends on [n]: HAS_IOMEM [=n] Selected by [y]: - MFD_HI6421_SPMI [=y] && STAGING [=y] && OF [=y] && SPMI [=y] # Added to kconfig CONFIG_STANDALONE=y # Added to kconfig CONFIG_KCOV=n # Added to kconfig CONFIG_GCC_PLUGINS=n # Added to kconfig CONFIG_GCC_PLUGIN_CYC_COMPLEXITY=n # Added to kconfig CONFIG_GCC_PLUGIN_SANCOV=n # Added to kconfig CONFIG_GCC_PLUGIN_LATENT_ENTROPY=n # Added to kconfig CONFIG_GCC_PLUGIN_STRUCTLEAK=n # Added to kconfig CONFIG_GCC_PLUGIN_RANDSTRUCT=n # Added to kconfig CONFIG_UML_NET=n # Added to kconfig CONFIG_UML_NET_ETHERTAP=n # Added to kconfig CONFIG_UML_NET_TUNTAP=n # Added to kconfig CONFIG_UML_NET_SLIP=n # Added to kconfig CONFIG_UML_NET_DAEMON=n # Added to kconfig CONFIG_UML_NET_VDE=n # Added to kconfig CONFIG_UML_NET_MCAST=n # Added to kconfig CONFIG_UML_NET_PCAP=n # Added to kconfig CONFIG_UML_NET_SLIRP=n # Added to kconfig CONFIG_GCOV_KERNEL=n # Added to kconfig CONFIG_DEBUG_INFO_BTF=n # < make -s -j 80 ARCH=um O=/kisskb/build/linus_um-allyesconfig_um-x86_64 CROSS_COMPILE=/opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux- SUBARCH=x86_64 help # make -s -j 80 ARCH=um O=/kisskb/build/linus_um-allyesconfig_um-x86_64 CROSS_COMPILE=/opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux- SUBARCH=x86_64 olddefconfig .config:4389:warning: override: reassigning to symbol UML_NET_ETHERTAP .config:4391:warning: override: reassigning to symbol UML_NET_SLIP .config:4394:warning: override: reassigning to symbol UML_NET_MCAST .config:4396:warning: override: reassigning to symbol UML_NET_SLIRP WARNING: unmet direct dependencies detected for MFD_CORE Depends on [n]: HAS_IOMEM [=n] Selected by [y]: - MFD_HI6421_SPMI [=y] && STAGING [=y] && OF [=y] && SPMI [=y] # make -s -j 80 ARCH=um O=/kisskb/build/linus_um-allyesconfig_um-x86_64 CROSS_COMPILE=/opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux- SUBARCH=x86_64 WARNING: unmet direct dependencies detected for MFD_CORE Depends on [n]: HAS_IOMEM [=n] Selected by [y]: - MFD_HI6421_SPMI [=y] && STAGING [=y] && OF [=y] && SPMI [=y] WARNING: unmet direct dependencies detected for MFD_CORE Depends on [n]: HAS_IOMEM [=n] Selected by [y]: - MFD_HI6421_SPMI [=y] && STAGING [=y] && OF [=y] && SPMI [=y] WARNING: unmet direct dependencies detected for MFD_CORE Depends on [n]: HAS_IOMEM [=n] Selected by [y]: - MFD_HI6421_SPMI [=y] && STAGING [=y] && OF [=y] && SPMI [=y] /kisskb/src/arch/um/os-Linux/signal.c: In function 'sig_handler_common': /kisskb/src/arch/um/os-Linux/signal.c:51:1: warning: the frame size of 2976 bytes is larger than 2048 bytes [-Wframe-larger-than=] } ^ /kisskb/src/arch/um/os-Linux/signal.c: In function 'timer_real_alarm_handler': /kisskb/src/arch/um/os-Linux/signal.c:95:1: warning: the frame size of 2960 bytes is larger than 2048 bytes [-Wframe-larger-than=] } ^ Auto-detecting system features: ... libelf: [ OFF ] ... zlib: [ OFF ] ... bpf: [ on ] No libelf found make[5]: *** [Makefile:287: elfdep] Error 1 make[4]: *** [/kisskb/src/kernel/bpf/preload/Makefile:8: kernel/bpf/preload/libbpf.a] Error 2 make[3]: *** [/kisskb/src/scripts/Makefile.build:500: kernel/bpf/preload] Error 2 make[3]: *** Waiting for unfinished jobs.... make[2]: *** [/kisskb/src/scripts/Makefile.build:500: kernel/bpf] Error 2 make[2]: *** Waiting for unfinished jobs.... make[1]: *** [/kisskb/src/Makefile:1799: kernel] Error 2 make[1]: *** Waiting for unfinished jobs.... /kisskb/src/lib/lz4/lz4hc_compress.c: In function 'LZ4HC_compress_generic': /kisskb/src/lib/lz4/lz4hc_compress.c:579:1: warning: the frame size of 2144 bytes is larger than 2048 bytes [-Wframe-larger-than=] } ^ make: *** [Makefile:185: __sub-make] Error 2 Command 'make -s -j 80 ARCH=um O=/kisskb/build/linus_um-allyesconfig_um-x86_64 CROSS_COMPILE=/opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux- SUBARCH=x86_64 ' returned non-zero exit status 2 # rm -rf /kisskb/build/linus_um-allyesconfig_um-x86_64 # Build took: 0:05:42.885362