linux-kernel - [RFC PATCH v2 0/3] getcpu

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Message-Id: <1453913683-28915-1-git-send-email-mathieu.desnoyers@efficios.com>
Date:	Wed, 27 Jan 2016 11:54:40 -0500
From:	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:	Thomas Gleixner <tglx@...utronix.de>, Paul Turner <pjt@...gle.com>,
	Andrew Hunter <ahh@...gle.com>,
	Peter Zijlstra <peterz@...radead.org>
Cc:	linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
	Andy Lutomirski <luto@...capital.net>,
	Andi Kleen <andi@...stfloor.org>,
	Dave Watson <davejwatson@...com>, Chris Lameter <cl@...ux.com>,
	Ingo Molnar <mingo@...hat.com>, Ben Maurer <bmaurer@...com>,
	Steven Rostedt <rostedt@...dmis.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Josh Triplett <josh@...htriplett.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Russell King <linux@....linux.org.uk>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Michael Kerrisk <mtk.manpages@...il.com>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Subject: [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

-- 
2.1.4