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[66.111.4.228]) by smtp.gmail.com with ESMTPSA id v137sm2795917qka.110.2020.12.09.19.08.57 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 09 Dec 2020 19:08:57 -0800 (PST) Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by mailauth.nyi.internal (Postfix) with ESMTP id CA9F527C0054; Wed, 9 Dec 2020 22:08:56 -0500 (EST) Received: from mailfrontend1 ([10.202.2.162]) by compute3.internal (MEProxy); Wed, 09 Dec 2020 22:08:56 -0500 X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedujedrudejledgheefucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepfffhvffukfhfgggtuggjsehttdertddttddvnecuhfhrohhmpeeuohhquhhn ucfhvghnghcuoegsohhquhhnrdhfvghnghesghhmrghilhdrtghomheqnecuggftrfgrth htvghrnhepveeijedthfeijeefudehhedvveegudegteehgffgtddvuedtveegtedvvdef gedtnecuffhomhgrihhnpehkvghrnhgvlhdrohhrghenucfkphepudeijedrvddvtddrvd druddvieenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhm pegsohhquhhnodhmvghsmhhtphgruhhthhhpvghrshhonhgrlhhithihqdeiledvgeehtd eigedqudejjeekheehhedvqdgsohhquhhnrdhfvghngheppehgmhgrihhlrdgtohhmsehf ihigmhgvrdhnrghmvg X-ME-Proxy: Received: from localhost (unknown [167.220.2.126]) by mail.messagingengine.com (Postfix) with ESMTPA id 3CC20240065; Wed, 9 Dec 2020 22:08:55 -0500 (EST) Date: Thu, 10 Dec 2020 11:08:54 +0800 From: Boqun Feng To: "Paul E. McKenney" Cc: Frederic Weisbecker , LKML , Steven Rostedt , Thomas Gleixner , Mathieu Desnoyers , Lai Jiangshan , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , rcu@vger.kernel.org Subject: Re: [PATCH 00/19] rcu/nocb: De-offload and re-offload support v4 Message-ID: <20201210030854.GA2958157@boqun-archlinux> References: <20201113121334.166723-1-frederic@kernel.org> <20201208024131.GI3025@boqun-archlinux> <20201208125104.GB16597@lothringen> <20201210012158.GO2657@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201210012158.GO2657@paulmck-ThinkPad-P72> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 09, 2020 at 05:21:58PM -0800, Paul E. McKenney wrote: > On Tue, Dec 08, 2020 at 01:51:04PM +0100, Frederic Weisbecker wrote: > > Hi Boqun Feng, > > > > On Tue, Dec 08, 2020 at 10:41:31AM +0800, Boqun Feng wrote: > > > Hi Frederic, > > > > > > On Fri, Nov 13, 2020 at 01:13:15PM +0100, Frederic Weisbecker wrote: > > > > This keeps growing up. Rest assured, most of it is debug code and sanity > > > > checks. > > > > > > > > Boqun Feng found that holding rnp lock while updating the offloaded > > > > state of an rdp isn't needed, and he was right despite my initial > > > > reaction. The sites that read the offloaded state while holding the rnp > > > > lock are actually protected because they read it locally in a non > > > > preemptible context. > > > > > > > > So I removed the rnp lock in "rcu/nocb: De-offloading CB". And just to > > > > make sure I'm not missing something, I added sanity checks that ensure > > > > we always read the offloaded state in a safe way (3 last patches). > > > > > > > > Still passes TREE01 (but I had to fight!) > > > > > > > > git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git > > > > rcu/nocb-toggle-v4 > > > > > > > > HEAD: 579e15efa48fb6fc4ecf14961804051f385807fe > > > > > > > > > > This whole series look good to me, plus I've run a test, so far > > > everything seems working ;-) Here is my setup for the test: > > > > > > I'm using a ARM64 guest (running on Hyper-V) to do the test, and the > > > guest has 8 VCPUs. The code I'm using is v5.10-rc6 + Hyper-V ARM64 guest > > > support [1] + your patchset (I actually did a merge from your > > > rcu/nocb-toggle-v5 branch, because IIUC some modification for rcutorture > > > is still in Paul's tree). I compiled with my normal configuration for > > > ARM64 Hyper-V guest plus TREE01, boot the kernel with: > > > > > > ignore_loglevel rcutree.gp_preinit_delay=3 rcutree.gp_init_delay=3 rcutree.gp_cleanup_delay=3 rcu_nocbs=0-1,3-7 > > > > > > and run rcutorture via: > > > > > > modprobe rcutorture nocbs_nthreads=8 nocbs_toggle=1000 fwd_progress=0 > > > > > > I ran the rcutorture twice, one last for a week or so and one for a day > > > or two and I didn't observe any problem so far. The latest test summary > > > is: > > > > > > [...] rcu-torture: rtc: 00000000f794686f ver: 2226396 tfle: 0 rta: 2226397 rtaf: 0 rtf: 2226385 rtmbe: 0 rtmbkf: 0/1390141 rtbe: 0 rtbke: 0 rtbre: 0 rtbf: 0 rtb: 0 nt: 181415346 onoff: 0/0:0/0 -1,0:-1,0 0:0 (HZ=1000) barrier: 0/0:0 read-exits: 108102 nocb-toggles: 306964:306974 > > > > > > Is there anything I'm missing for a useful test? Do you have other setup > > > (kernel cmdline or rcutorture parameters) that you want me to try? > > > > Thanks a lot for reviewing and testing. You seem to have tested with the right > > options, I have nothing better to suggest. Plus I'm glad you tested on > > ARM64. x86 is the only target I have tested so far. > > Boqun, would you be willing to give your Tested-by? > Sure, FWIW, for the whole series, feel free to add: Tested-by: Boqun Feng Regards, Boqun > Thanx, Paul