Hi, Here is a patchset implementing a cache for the CPU number of the currently running thread in user-space. Benchmarks comparing this approach to a system call-based getcpu on ARM show a 44x speedup. They show a 14x speedup on x86-64 compared to executing lsl from a vDSO through glibc. I'm added a man page in the changelog of patch 1/3, which shows an example usage of this new system call. This patchset is sent as RFC. It applies on Linux 4.3. Feedback is welcome, Thanks! Mathieu Mathieu Desnoyers (3): getcpu_cache system call: cache CPU number of running thread getcpu_cache: wire up ARM system call getcpu_cache: wire up x86 32/64 system call arch/arm/include/uapi/asm/unistd.h | 1 + arch/arm/kernel/calls.S | 1 + arch/arm/kernel/signal.c | 1 + arch/x86/entry/common.c | 1 + arch/x86/entry/syscalls/syscall_32.tbl | 1 + arch/x86/entry/syscalls/syscall_64.tbl | 1 + fs/exec.c | 1 + include/linux/init_task.h | 8 ++ include/linux/sched.h | 43 +++++++++ include/uapi/linux/Kbuild | 1 + include/uapi/linux/getcpu_cache.h | 44 +++++++++ init/Kconfig | 10 ++ kernel/Makefile | 1 + kernel/fork.c | 7 ++ kernel/getcpu_cache.c | 170 +++++++++++++++++++++++++++++++++ kernel/sched/core.c | 3 + kernel/sched/sched.h | 1 + kernel/sys_ni.c | 3 + 18 files changed, 298 insertions(+) create mode 100644 include/uapi/linux/getcpu_cache.h create mode 100644 kernel/getcpu_cache.c -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
