[RFC PATCH v2 0/3] getcpu_cache system call

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 getcpu based on system call 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 4.4.

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

 MAINTAINERS                            |   6 ++
 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/sched.h                  |  36 +++++++++++
 init/Kconfig                           |  10 ++++
 kernel/Makefile                        |   1 +
 kernel/fork.c                          |   4 ++
 kernel/getcpu_cache.c                  | 106 +++++++++++++++++++++++++++++++++
 kernel/sched/sched.h                   |   1 +
 kernel/sys_ni.c                        |   3 +
 15 files changed, 174 insertions(+)
 create mode 100644 kernel/getcpu_cache.c

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2.1.4