On Tue, Oct 01, 2024 at 09:02:01PM -0400, Mathieu Desnoyers wrote:
> Hazard pointers appear to be a good fit for replacing refcount based lazy
> active mm tracking.
>
> Highlight:
>
> will-it-scale context_switch1_threads
>
> nr threads (-t) speedup
> 24 +3%
> 48 +12%
> 96 +21%
> 192 +28%
Impressive!!!
I have to ask... Any data for smaller numbers of CPUs?
Thanx, Paul
> I'm curious to see what the build bots have to say about this.
>
> This series applies on top of v6.11.1.
>
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoy...@efficios.com>
> Cc: Nicholas Piggin <npig...@gmail.com>
> Cc: Michael Ellerman <m...@ellerman.id.au>
> Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
> Cc: Sebastian Andrzej Siewior <bige...@linutronix.de>
> Cc: "Paul E. McKenney" <paul...@kernel.org>
> Cc: Will Deacon <w...@kernel.org>
> Cc: Boqun Feng <boqun.f...@gmail.com>
> Cc: Alan Stern <st...@rowland.harvard.edu>
> Cc: John Stultz <jstu...@google.com>
> Cc: Neeraj Upadhyay <neeraj.upadh...@amd.com>
> Cc: Boqun Feng <boqun.f...@gmail.com>
> Cc: Frederic Weisbecker <frede...@kernel.org>
> Cc: Joel Fernandes <j...@joelfernandes.org>
> Cc: Josh Triplett <j...@joshtriplett.org>
> Cc: Uladzislau Rezki <ure...@gmail.com>
> Cc: Steven Rostedt <rost...@goodmis.org>
> Cc: Lai Jiangshan <jiangshan...@gmail.com>
> Cc: Zqiang <qiang.zhang1...@gmail.com>
> Cc: Ingo Molnar <mi...@redhat.com>
> Cc: Waiman Long <long...@redhat.com>
> Cc: Mark Rutland <mark.rutl...@arm.com>
> Cc: Thomas Gleixner <t...@linutronix.de>
> Cc: Vlastimil Babka <vba...@suse.cz>
> Cc: maged.mich...@gmail.com
> Cc: Mateusz Guzik <mjgu...@gmail.com>
> Cc: Jonas Oberhauser <jonas.oberhau...@huaweicloud.com>
> Cc: r...@vger.kernel.org
> Cc: linux...@kvack.org
> Cc: l...@lists.linux.dev
>
> Mathieu Desnoyers (4):
> compiler.h: Introduce ptr_eq() to preserve address dependency
> Documentation: RCU: Refer to ptr_eq()
> hp: Implement Hazard Pointers
> sched+mm: Use hazard pointers to track lazy active mm existence
>
> Documentation/RCU/rcu_dereference.rst | 38 ++++++-
> Documentation/mm/active_mm.rst | 9 +-
> arch/Kconfig | 32 ------
> arch/powerpc/Kconfig | 1 -
> arch/powerpc/mm/book3s64/radix_tlb.c | 23 +---
> include/linux/compiler.h | 63 +++++++++++
> include/linux/hp.h | 154 ++++++++++++++++++++++++++
> include/linux/mm_types.h | 3 -
> include/linux/sched/mm.h | 71 +++++-------
> kernel/Makefile | 2 +-
> kernel/exit.c | 4 +-
> kernel/fork.c | 47 ++------
> kernel/hp.c | 46 ++++++++
> kernel/sched/sched.h | 8 +-
> lib/Kconfig.debug | 10 --
> 15 files changed, 346 insertions(+), 165 deletions(-)
> create mode 100644 include/linux/hp.h
> create mode 100644 kernel/hp.c
>
> --
> 2.39.2
