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[103.168.172.201]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-88d9624015asm330396376d6.6.2026.01.01.00.41.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 01 Jan 2026 00:41:22 -0800 (PST) Received: from phl-compute-01.internal (phl-compute-01.internal [10.202.2.41]) by mailfauth.phl.internal (Postfix) with ESMTP id B7B5DF40068; Thu, 1 Jan 2026 03:41:21 -0500 (EST) Received: from phl-frontend-03 ([10.202.2.162]) by phl-compute-01.internal (MEProxy); Thu, 01 Jan 2026 03:41:21 -0500 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeefgedrtddtgdekheefvdcutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpuffrtefokffrpgfnqfghnecuuegr ihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjug hrpeffhffvvefukfhfgggtuggjsehttdertddttddvnecuhfhrohhmpeeuohhquhhnucfh vghnghcuoegsohhquhhnrdhfvghnghesghhmrghilhdrtghomheqnecuggftrfgrthhtvg hrnhephfetvdfgtdeukedvkeeiteeiteejieehvdetheduudejvdektdekfeegvddvhedt necuffhomhgrihhnpehkvghrnhgvlhdrohhrghenucevlhhushhtvghrufhiiigvpedtne curfgrrhgrmhepmhgrihhlfhhrohhmpegsohhquhhnodhmvghsmhhtphgruhhthhhpvghr shhonhgrlhhithihqdeiledvgeehtdeigedqudejjeekheehhedvqdgsohhquhhnrdhfvg hngheppehgmhgrihhlrdgtohhmsehfihigmhgvrdhnrghmvgdpnhgspghrtghpthhtohep jedpmhhouggvpehsmhhtphhouhhtpdhrtghpthhtohepjhhovghlrghgnhgvlhhfsehnvh hiughirgdrtghomhdprhgtphhtthhopehprghulhhmtghksehkvghrnhgvlhdrohhrghdp rhgtphhtthhopehrtghusehvghgvrhdrkhgvrhhnvghlrdhorhhgpdhrtghpthhtoheplh hinhhugidqkhgvrhhnvghlsehvghgvrhdrkhgvrhhnvghlrdhorhhgpdhrtghpthhtohep khgvrhhnvghlqdhtvggrmhesmhgvthgrrdgtohhmpdhrtghpthhtoheprhhoshhtvgguth esghhoohgumhhishdrohhrghdprhgtphhtthhopegsohhquhhnsehfihigmhgvrdhnrghm vg X-ME-Proxy: Feedback-ID: iad51458e:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Thu, 1 Jan 2026 03:41:20 -0500 (EST) Date: Thu, 1 Jan 2026 16:41:12 +0800 From: Boqun Feng To: Joel Fernandes Cc: "Paul E. McKenney" , rcu@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, rostedt@goodmis.org Subject: Re: [PATCH v4 0/9] Implement RCU Tasks Trace in terms of SRCU for post-v4.19 Message-ID: References: <20251230231911.GA2605197@joelbox2> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251230231911.GA2605197@joelbox2> On Tue, Dec 30, 2025 at 06:19:11PM -0500, Joel Fernandes wrote: > On Mon, Dec 29, 2025 at 11:10:55AM -0800, Paul E. McKenney wrote: > > Hello! > > > > This v4 patch series re-implements RCU Tasks Trace in terms of SRCU-fast, > > reducing the size of the Linux-kernel RCU implementation by several > > hundred lines of code. The patches are as follows: > > > > 1. Re-implement RCU Tasks Trace in terms of SRCU-fast. > > > > 2. context_tracking: Remove > > rcu_task_trace_heavyweight_{enter,exit}(). > > > > 3. Clean up after the SRCU-fastification of RCU Tasks Trace. > > > > 4. Move rcu_tasks_trace_srcu_struct out of #ifdef > > CONFIG_TASKS_RCU_GENERIC. > > > > 5. Add noinstr-fast rcu_read_{,un}lock_tasks_trace() APIs. > > > > 6. Update Requirements.rst for RCU Tasks Trace. > > > > 7. Deprecate rcu_read_{,un}lock_trace(). > > > > 8. Create an rcu_tasks_trace_expedite_current() function. > > > > 9. Test rcu_tasks_trace_expedite_current(). > > > > Changes since v3: > > > > o Rebase onto v6.19-rc1. > > > > o Wait for arm64 per-CPU variable speedups to reach mainline. > > > > https://lore.kernel.org/all/a1e505e4-931b-45cf-8ca7-337442aa598e@paulmck-laptop/#r > > > > Changes since v2: > > > > o SRCU improvments not strictly related to RCU tasks trace have > > been moved out to a separate series. > > > > o Use the new DEFINE_SRCU_FAST(). > > > > https://lore.kernel.org/all/7fa58961-2dce-4e08-8174-1d1cc592210f@paulmck-laptop/ > > > > Changes since v1: > > > > o Consolidate RCU Tasks Trace cleanup patches per Alexei Starovoitov > > feedback. This explains the decrease from 34 patches in v1 to > > only 21 in this v2 series. > > > > o While consolidating, consolidate the noinstr-fast patches and the > > DEFINE_SRCU_FAST()/init_srcu_struct_fast() patches. > > > > o Upgrade comments per Peter Zijlstra feedback. > > > > o Extract Tiny SRCU bug fix into its own commit per Andrii Nakryiko > > feedback. > > > > o Switch srcu_expedite_current() from preempt_disable() to > > migrate_disable() for PREEMPT_RT kernels per Zqiang feedback. > > > > o Apply tags. > > > > https://lore.kernel.org/all/580ea2de-799a-4ddc-bde9-c16f3fb1e6e7@paulmck-laptop/ > > > > Thanx, Paul > > > > ------------------------------------------------------------------------ > > > > b/Documentation/RCU/Design/Requirements/Requirements.rst | 12 > > b/Documentation/admin-guide/kernel-parameters.txt | 15 > > b/include/linux/rcupdate.h | 31 > > b/include/linux/rcupdate_trace.h | 107 +- > > b/include/linux/sched.h | 1 > > b/init/init_task.c | 3 > > b/kernel/context_tracking.c | 20 > > b/kernel/fork.c | 3 > > b/kernel/rcu/Kconfig | 18 > > b/kernel/rcu/rcu.h | 9 > > b/kernel/rcu/rcuscale.c | 7 > > b/kernel/rcu/rcutorture.c | 2 > > b/kernel/rcu/tasks.h | 621 --------------- > > b/scripts/checkpatch.pl | 4 > > b/tools/testing/selftests/rcutorture/configs/rcu/TRACE01 | 1 > > b/tools/testing/selftests/rcutorture/configs/rcu/TRACE02 | 1 > > include/linux/rcupdate_trace.h | 81 + > > include/linux/sched.h | 5 > > kernel/rcu/Kconfig | 25 > > kernel/rcu/rcutorture.c | 1 > > kernel/rcu/tasks.h | 121 -- > > 21 files changed, 219 insertions(+), 869 deletions(-) > > Reviewed-by: Joel Fernandes > Queued, thank you both! Regards, Boqun > thanks > >