Hi, This patchset implements a general ABI to exchange per-thread data between kernel and user-space. The initial feature implemented is a cache for the CPU number of the currently running thread in user-space. This ABI is extensible to add more features in the future. Benchmarks comparing this approach to a getcpu based on system call on ARM show a 44x speedup. They show a 16.5x speedup on x86-64 compared to executing lsl from a vDSO through glibc. There is a man page in the changelog of patch 1/5, which shows an example usage of this new system call. This patchset is sent as RFC. It applies on Linux 4.5. The prior versions of this patchset were known as a "getcpu_cache system call". Feedback is welcome, Thanks! Mathieu Mathieu Desnoyers (5): Thread-local ABI system call: cache CPU number of running thread Thread-local ABI cpu_id: ARM resume notifier Thread-local ABI: wire up ARM system call Thread-local ABI cpu_id: x86 32/64 resume notifier Thread-local ABI: wire up x86 32/64 system call MAINTAINERS | 7 +++ arch/arm/include/asm/unistd.h | 2 +- arch/arm/include/uapi/asm/unistd.h | 1 + arch/arm/kernel/calls.S | 3 +- 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/sched.h | 66 +++++++++++++++++++++ include/uapi/linux/Kbuild | 1 + include/uapi/linux/thread_local_abi.h | 83 ++++++++++++++++++++++++++ init/Kconfig | 14 +++++ kernel/Makefile | 1 + kernel/fork.c | 4 ++ kernel/sched/sched.h | 1 + kernel/sys_ni.c | 3 + kernel/thread_local_abi.c | 103 +++++++++++++++++++++++++++++++++ 18 files changed, 292 insertions(+), 2 deletions(-) create mode 100644 include/uapi/linux/thread_local_abi.h create mode 100644 kernel/thread_local_abi.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
