# git rev-parse -q --verify 62906027091f1d02de44041524f0769f60bb9cf3^{commit} 62906027091f1d02de44041524f0769f60bb9cf3 already have revision, skipping fetch # git checkout -q -f -B kisskb 62906027091f1d02de44041524f0769f60bb9cf3 # git clean -qxdf # git log -1 commit 62906027091f1d02de44041524f0769f60bb9cf3 Author: Nicholas Piggin Date: Sun Dec 25 13:00:30 2016 +1000 mm: add PageWaiters indicating tasks are waiting for a page bit Add a new page flag, PageWaiters, to indicate the page waitqueue has tasks waiting. This can be tested rather than testing waitqueue_active which requires another cacheline load. This bit is always set when the page has tasks on page_waitqueue(page), and is set and cleared under the waitqueue lock. It may be set when there are no tasks on the waitqueue, which will cause a harmless extra wakeup check that will clears the bit. The generic bit-waitqueue infrastructure is no longer used for pages. Instead, waitqueues are used directly with a custom key type. The generic code was not flexible enough to have PageWaiters manipulation under the waitqueue lock (which simplifies concurrency). This improves the performance of page lock intensive microbenchmarks by 2-3%. Putting two bits in the same word opens the opportunity to remove the memory barrier between clearing the lock bit and testing the waiters bit, after some work on the arch primitives (e.g., ensuring memory operand widths match and cover both bits). Signed-off-by: Nicholas Piggin Cc: Dave Hansen Cc: Bob Peterson Cc: Steven Whitehouse Cc: Andrew Lutomirski Cc: Andreas Gruenbacher Cc: Peter Zijlstra Cc: Mel Gorman Signed-off-by: Linus Torvalds # < /opt/cross/kisskb/gcc-4.6.3-nolibc/i386-linux/bin/i386-linux-gcc --version # < git log --format=%s --max-count=1 62906027091f1d02de44041524f0769f60bb9cf3 # < make -j 10 ARCH=i386 O=/home/kisskb/slave/build/linus_i386-randconfig_i386 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/i386-linux/bin/i386-linux- randconfig KCONFIG_SEED=0x980B2C88 # Added to kconfig CONFIG_STANDALONE=y # Added to kconfig CONFIG_PREVENT_FIRMWARE_BUILD=y # yes \n | make -j 10 ARCH=i386 O=/home/kisskb/slave/build/linus_i386-randconfig_i386 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/i386-linux/bin/i386-linux- oldconfig yes: standard output: Broken pipe yes: write error # make -j 10 ARCH=i386 O=/home/kisskb/slave/build/linus_i386-randconfig_i386 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/i386-linux/bin/i386-linux- make[1]: Entering directory '/home/kisskb/slave/build/linus_i386-randconfig_i386' GEN ./Makefile scripts/kconfig/conf --silentoldconfig Kconfig SYSTBL arch/x86/entry/syscalls/../../include/generated/asm/syscalls_32.h SYSHDR arch/x86/entry/syscalls/../../include/generated/uapi/asm/unistd_32.h SYSHDR arch/x86/entry/syscalls/../../include/generated/uapi/asm/unistd_64.h SYSHDR arch/x86/entry/syscalls/../../include/generated/uapi/asm/unistd_x32.h HOSTCC scripts/basic/bin2c CHK include/config/kernel.release UPD include/config/kernel.release Cannot use CONFIG_CC_STACKPROTECTOR_REGULAR: -fstack-protector available but compiler is broken /home/kisskb/slave/src/Makefile:1073: recipe for target 'prepare-compiler-check' failed make[1]: *** [prepare-compiler-check] Error 1 make[1]: *** Waiting for unfinished jobs.... make[1]: *** wait: No child processes. Stop. Makefile:150: recipe for target 'sub-make' failed make: *** [sub-make] Error 2 Command 'make -j 10 ARCH=i386 O=/home/kisskb/slave/build/linus_i386-randconfig_i386 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/i386-linux/bin/i386-linux- ' returned non-zero exit status 2 # rm -rf /home/kisskb/slave/build/linus_i386-randconfig_i386 # Build took: 0:00:06.659856