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Received: from willy by casper.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1sw1M9-00000005gCA-3fpE; Wed, 02 Oct 2024 15:33:37 +0000 Date: Wed, 2 Oct 2024 16:33:37 +0100 From: Matthew Wilcox To: Mathieu Desnoyers Cc: paulmck@kernel.org, Linus Torvalds , Andrew Morton , Peter Zijlstra , linux-kernel@vger.kernel.org, Nicholas Piggin , Michael Ellerman , Greg Kroah-Hartman , Sebastian Andrzej Siewior , Will Deacon , Boqun Feng , Alan Stern , John Stultz , Neeraj Upadhyay , Frederic Weisbecker , Joel Fernandes , Josh Triplett , Uladzislau Rezki , Steven Rostedt , Lai Jiangshan , Zqiang , Ingo Molnar , Waiman Long , Mark Rutland , Thomas Gleixner , Vlastimil Babka , maged.michael@gmail.com, Mateusz Guzik , Jonas Oberhauser , rcu@vger.kernel.org, linux-mm@kvack.org, lkmm@lists.linux.dev Subject: Re: [RFC PATCH 0/4] sched+mm: Track lazy active mm existence with hazard pointers Message-ID: References: <20241002010205.1341915-1-mathieu.desnoyers@efficios.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Stat-Signature: zqymxnqms5x47xpbg16t9c5rqbxpke8f X-Rspamd-Queue-Id: 1B5F540002 X-Rspamd-Server: rspam11 X-HE-Tag: 1727883239-725698 X-HE-Meta: U2FsdGVkX18FSpfgJns1tj4gTe0yNewwUE1MoIr4uOQ+y7RK0frKZiLK2eoUAFltP7uCiqfLD1SEwfvWTLrPRo8fuKFHh2Lr3xMFEZEgqDLPMqkmBABUDFtb7j0o9z2LQrQD7ZlnD2iA+beizZygZ8GYsJmodZpNhHDcMIULz8DtTXWjcetlq4we4Bv8yayTCytqvRdNkIbA2ySzuWcFCJeYi01kQwhfnNbdULW3PEBVrXOzMUAcfQewAuWwTM18Zf3OspjPmmx6q0ah4nKyhIBiXNeaEPOep/NEeeLbFL4V9PHQDz8+2ythBoIEn5bAbINVJWrZPV1Gi7lmqHqysWH+Xwv9jv8f+tLZANUYqK2bjK502kAGg8qMXK+BNWc6qfHOLZ9lTDDgnUkLyMnAheypd52OQ8OqorJ+ojByDRAG8Awf5fUqdTcoxpuil8QvO1GhicTMWYoBwMTxui3LcmH73ES/V59bMk3l1/r/aaHTl2+xB1GgDJOF5ge4cjE90VmXEBFTqBIFud6mq97iH75d8paHb4CT2iViC4lluWGz8YAsyfX3cxR0YULDQpRi8KmVY+1Tm+qoywXOz9dUJR5qmHlN+Xkxc10XDy81Ru6X8FxctnY6ryoOMbOLsXPAV4KZH+iY7annFpWFvA1AOIgXrfW+wf+jxSY23ADMRLj3Vhc3LEOfPL7pU5d6z3aC4sIkULzZ1GBomPhHE+Ko5faYjPRCL9rWS35b26lwo9fRzGshaETGyGgNBdqVrA3dPhf8T/hpawOpCeVcxWh10oxpTNbUt5RlIzOGoJhqv+AVm/f7/evmwUzyWGfEysRZ8HPJp4LRAk2T5gU6+TlEDZMLkN2klVlLV5XKf7jkZeRWIPOA0l/9XsCxBYaE4RnMOGcUX0D1j/q+VY+4auCky8C3i8Rp9GgFp/CBEhwRh9RISpkLOGF1iIroj7VJdZcXeDGoiWlLseoe4hXjr+q JO4ewspd 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Oct 02, 2024 at 11:26:27AM -0400, Mathieu Desnoyers wrote: > On 2024-10-02 16:09, Paul E. McKenney wrote: > > 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? > > Sure, but they are far less exciting ;-) How many CPUs in the system under test? > nr threads (-t) speedup > 1 -0.2% > 2 +0.4% > 3 +0.2% > 6 +0.6% > 12 +0.8% > 24 +3% > 48 +12% > 96 +21% > 192 +28% > 384 +4% > 768 -0.6% > > Thanks, > > Mathieu > > > > > 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 > > > Cc: Nicholas Piggin > > > Cc: Michael Ellerman > > > Cc: Greg Kroah-Hartman > > > Cc: Sebastian Andrzej Siewior > > > Cc: "Paul E. McKenney" > > > Cc: Will Deacon > > > Cc: Boqun Feng > > > Cc: Alan Stern > > > Cc: John Stultz > > > Cc: Neeraj Upadhyay > > > Cc: Boqun Feng > > > Cc: Frederic Weisbecker > > > Cc: Joel Fernandes > > > Cc: Josh Triplett > > > Cc: Uladzislau Rezki > > > Cc: Steven Rostedt > > > Cc: Lai Jiangshan > > > Cc: Zqiang > > > Cc: Ingo Molnar > > > Cc: Waiman Long > > > Cc: Mark Rutland > > > Cc: Thomas Gleixner > > > Cc: Vlastimil Babka > > > Cc: maged.michael@gmail.com > > > Cc: Mateusz Guzik > > > Cc: Jonas Oberhauser > > > Cc: rcu@vger.kernel.org > > > Cc: linux-mm@kvack.org > > > Cc: lkmm@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 > > -- > Mathieu Desnoyers > EfficiOS Inc. > https://www.efficios.com > >