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From: Mark Rutland <mark.rutland@arm.com>
To: Frederic Weisbecker <frederic@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Phil Auld <pauld@redhat.com>, Alex Belits <abelits@marvell.com>,
	Nicolas Saenz Julienne <nsaenz@kernel.org>,
	Xiongfeng Wang <wangxiongfeng2@huawei.com>,
	Neeraj Upadhyay <quic_neeraju@quicinc.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Yu Liao <liaoyu15@huawei.com>, Boqun Feng <boqun.feng@gmail.com>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Paul Gortmaker <paul.gortmaker@windriver.com>,
	Uladzislau Rezki <uladzislau.rezki@sony.com>,
	Joel Fernandes <joel@joelfernandes.org>
Subject: Re: [PATCH 10/21] context_tracking: Take idle eqs entrypoints over RCU
Date: Tue, 3 May 2022 14:33:22 +0100	[thread overview]
Message-ID: <YnEvIhNVOEDyS6/A@lakrids> (raw)
In-Reply-To: <20220503114225.GA2799075@lothringen>

On Tue, May 03, 2022 at 01:42:25PM +0200, Frederic Weisbecker wrote:
> On Tue, May 03, 2022 at 12:02:51PM +0100, Mark Rutland wrote:
> > Hi Frederic,
> > 
> > On Tue, May 03, 2022 at 12:00:40PM +0200, Frederic Weisbecker wrote:
> > > The RCU dynticks counter is going to be merged into the context tracking
> > > subsystem. Start with moving the idle extended quiescent states
> > > entrypoints to context tracking. For now those are dumb redirections to
> > > existing RCU calls.
> > 
> > I was a bit confused looking at this, because that redirection only exists for
> > CONFIG_CONTEXT_TRACKING, and is empty otherwise.
> > 
> > I see this patch makes TREE_RCU select CONTEXT_TRACKING, which means that
> > works. Since that also means building the rest of the context tracking code, I
> > think it'd be worth mentioning that in the commit message.
> 
> Not exactly, it only builds a minimal version of CONTEXT_TRACKING, which maps
> to roughly the vanilla RCU-idle code.
> 
> The user tracking part (which is the vanilla CONTEXT_TRACKING) now becomes
> CONFIG_CONTEXT_TRACKING_USER

Ah, sorry. That makes sense to me now!

> > Do all architectures which can use TREE_RCU today already support context
> > tracking? If not, do those work by default?
> 
> No need to, the old context tracking becomes CONFIG_CONTEXT_TRACKING_USER
> which is not needed by TREE_RCU.
> 
> Ok you're right, this is all very confusing :o)
> 
> Let's clarify this, I'm going to do the following on the next version:
> 
> * The current CONFIG_CONTEXT_TRACKING becomes CONFIG_CONTEXT_TRACKING_USER.
>   This part needs support from the architecture.
> 
> * The RCU-idle functions that have been moved to context tracking will become
>   CONFIG_CONTEXT_TRACKING_IDLE. This part doesn't need support from the
>   architecture and will be set by TREE_RCU.
> 
> Would that look clearer?

I think so, yes!

It would also help if the prior commit message could be explicit about
the end result: After the Kconfig rework both
CONFIG_CONTEXT_TRACKING_USER and CONFIG_CONTEXT_TRACKING exist, but
CONFIG_CONTEXT_TRACKING will only used to decide whether to build object
files with common context tracking logic.

Thanks,
Mark.

  reply	other threads:[~2022-05-03 13:33 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-03 10:00 [PATCH 00/21] rcu/context-tracking: Merge RCU eqs-dynticks counter to context tracking v2 Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 01/21] context_tracking: Remove unused context_tracking_in_user() Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 02/21] rcu: Set rcu_idle_enter() as noinstr Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 03/21] rcu: Add a note about noinstr VS unsafe eqs functions Frederic Weisbecker
2022-05-19 14:48   ` Peter Zijlstra
2022-05-19 15:01     ` Frederic Weisbecker
2022-05-19 14:54   ` Peter Zijlstra
2022-05-19 15:26     ` Paul E. McKenney
2022-05-19 15:35       ` Frederic Weisbecker
2022-05-19 16:10         ` Paul E. McKenney
2022-05-19 15:00   ` Peter Zijlstra
2022-05-19 15:04     ` Frederic Weisbecker
2022-05-19 21:43     ` Peter Zijlstra
2022-05-03 10:00 ` [PATCH 04/21] context_tracking: Add a note about noinstr VS unsafe context tracking functions Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 05/21] context_tracking: Rename __context_tracking_enter/exit() to __ct_user_enter/exit() Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 06/21] context_tracking: Rename context_tracking_user_enter/exit() to user_enter/exit_callable() Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 07/21] context_tracking: Rename context_tracking_enter/exit() to ct_user_enter/exit() Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 08/21] context_tracking: Rename context_tracking_cpu_set() to ct_cpu_track_user() Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 09/21] context_tracking: Split user tracking Kconfig Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 10/21] context_tracking: Take idle eqs entrypoints over RCU Frederic Weisbecker
2022-05-03 11:02   ` Mark Rutland
2022-05-03 11:42     ` Frederic Weisbecker
2022-05-03 13:33       ` Mark Rutland [this message]
2022-05-03 10:00 ` [PATCH 11/21] context_tracking: Take IRQ " Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 12/21] context_tracking: Take NMI " Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 13/21] rcu/context-tracking: Remove rcu_irq_enter/exit() Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 14/21] rcu/context_tracking: Move dynticks counter to context tracking Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 15/21] rcu/context_tracking: Move dynticks_nesting " Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 16/21] rcu/context_tracking: Move dynticks_nmi_nesting " Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 17/21] rcu/context-tracking: Move deferred nocb resched " Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 18/21] rcu/context-tracking: Move RCU-dynticks internal functions to context_tracking Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 19/21] rcu/context-tracking: Remove unused and/or unecessary middle functions Frederic Weisbecker
2022-05-03 10:00 ` [PATCH 20/21] context_tracking: Convert state to atomic_t Frederic Weisbecker
2022-05-18 15:09   ` nicolas saenz julienne
2022-05-19 14:37     ` Frederic Weisbecker
2022-05-23 11:59       ` nicolas saenz julienne
2022-05-03 10:00 ` [PATCH 21/21] rcu/context_tracking: Merge dynticks counter and context tracking states Frederic Weisbecker
2022-05-18 15:31   ` nicolas saenz julienne
2022-05-19 15:06     ` Frederic Weisbecker
2022-05-18 15:33 ` [PATCH 00/21] rcu/context-tracking: Merge RCU eqs-dynticks counter to context tracking v2 Nicolas Saenz Julienne
2022-05-19 15:07   ` Frederic Weisbecker

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