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Fri, 24 Jul 2020 21:11:39 +0000 (UTC) Received: from llong.remote.csb (ovpn-117-203.rdu2.redhat.com [10.10.117.203]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9267410013C2; Fri, 24 Jul 2020 21:11:36 +0000 (UTC) Subject: Re: [PATCH v4 0/6] powerpc: queued spinlocks and rwlocks To: Nicholas Piggin , linuxppc-dev@lists.ozlabs.org References: <20200724131423.1362108-1-npiggin@gmail.com> From: Waiman Long Organization: Red Hat Message-ID: Date: Fri, 24 Jul 2020 17:11:36 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <20200724131423.1362108-1-npiggin@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, Peter Zijlstra , Boqun Feng , linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org, virtualization@lists.linux-foundation.org, Ingo Molnar , =?UTF-8?Q?Michal_Such=c3=a1nek?= , Will Deacon Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 7/24/20 9:14 AM, Nicholas Piggin wrote: > Updated with everybody's feedback (thanks all), and more performance > results. > > What I've found is I might have been measuring the worst load point for > the paravirt case, and by looking at a range of loads it's clear that > queued spinlocks are overall better even on PV, doubly so when you look > at the generally much improved worst case latencies. > > I have defaulted it to N even though I'm less concerned about the PV > numbers now, just because I think it needs more stress testing. But > it's very nicely selectable so should be low risk to include. > > All in all this is a very cool technology and great results especially > on the big systems but even on smaller ones there are nice gains. Thanks > Waiman and everyone who developed it. > > Thanks, > Nick > > Nicholas Piggin (6): > powerpc/pseries: move some PAPR paravirt functions to their own file > powerpc: move spinlock implementation to simple_spinlock > powerpc/64s: implement queued spinlocks and rwlocks > powerpc/pseries: implement paravirt qspinlocks for SPLPAR > powerpc/qspinlock: optimised atomic_try_cmpxchg_lock that adds the > lock hint > powerpc: implement smp_cond_load_relaxed > > arch/powerpc/Kconfig | 15 + > arch/powerpc/include/asm/Kbuild | 1 + > arch/powerpc/include/asm/atomic.h | 28 ++ > arch/powerpc/include/asm/barrier.h | 14 + > arch/powerpc/include/asm/paravirt.h | 87 +++++ > arch/powerpc/include/asm/qspinlock.h | 91 ++++++ > arch/powerpc/include/asm/qspinlock_paravirt.h | 7 + > arch/powerpc/include/asm/simple_spinlock.h | 288 ++++++++++++++++ > .../include/asm/simple_spinlock_types.h | 21 ++ > arch/powerpc/include/asm/spinlock.h | 308 +----------------- > arch/powerpc/include/asm/spinlock_types.h | 17 +- > arch/powerpc/lib/Makefile | 3 + > arch/powerpc/lib/locks.c | 12 +- > arch/powerpc/platforms/pseries/Kconfig | 9 +- > arch/powerpc/platforms/pseries/setup.c | 4 +- > include/asm-generic/qspinlock.h | 4 + > 16 files changed, 588 insertions(+), 321 deletions(-) > create mode 100644 arch/powerpc/include/asm/paravirt.h > create mode 100644 arch/powerpc/include/asm/qspinlock.h > create mode 100644 arch/powerpc/include/asm/qspinlock_paravirt.h > create mode 100644 arch/powerpc/include/asm/simple_spinlock.h > create mode 100644 arch/powerpc/include/asm/simple_spinlock_types.h > That patch series looks good to me. Thanks for working on this. For the series, Acked-by: Waiman Long