[RFC PATCH v3 0/5] getcpu_cache system call

[Mathieu Desnoyers <mathieu.desnoyers-vg+e7yoeK/dWk0Htik3J/w@public.gmane.org>]

Hi,

Here is an update to the getcpu_cache system call following the v2 round
of review. It implements 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.

This patchset is sent as RFC. It applies on Linux 4.4. It is submitted
for feedback. I'm targeting the 4.6 merge window.

Feedback is welcome,

Thanks!

Mathieu

Mathieu Desnoyers (5):
  getcpu_cache system call: cache CPU number of running thread
  getcpu_cache: ARM resume notifier
  getcpu_cache: wire up ARM system call
  getcpu_cache: x86 32/64 resume notifier
  getcpu_cache: wire up x86 32/64 system call

 MAINTAINERS                            |   7 ++
 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 ++++++++
 include/uapi/linux/Kbuild              |   1 +
 include/uapi/linux/getcpu_cache.h      |  42 +++++++++
 init/Kconfig                           |  10 +++
 kernel/Makefile                        |   1 +
 kernel/fork.c                          |   4 +
 kernel/getcpu_cache.c                  | 150 +++++++++++++++++++++++++++++++++
 kernel/sched/sched.h                   |   1 +
 kernel/sys_ni.c                        |   3 +
 17 files changed, 262 insertions(+)
 create mode 100644 include/uapi/linux/getcpu_cache.h
 create mode 100644 kernel/getcpu_cache.c

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2.1.4