Linux RCU subsystem development
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From: Frederic Weisbecker <frederic@kernel.org>
To: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: linux-kernel@vger.kernel.org, rcu@vger.kernel.org,
	x86@kernel.org, Lai Jiangshan <jiangshan.ljs@antgroup.com>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Neeraj Upadhyay <quic_neeraju@quicinc.com>,
	Joel Fernandes <joel@joelfernandes.org>,
	Josh Triplett <josh@joshtriplett.org>,
	Boqun Feng <boqun.feng@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Zqiang <qiang.zhang1211@gmail.com>
Subject: Re: [PATCH 08/10] rcu: Implement PCPU_RCU_PREEMPT_COUNT framework
Date: Mon, 22 Apr 2024 12:41:08 +0200	[thread overview]
Message-ID: <ZiY-xItV0IMrGDQH@localhost.localdomain> (raw)
In-Reply-To: <20240328075318.83039-9-jiangshanlai@gmail.com>

Le Thu, Mar 28, 2024 at 03:53:16PM +0800, Lai Jiangshan a écrit :
> From: Lai Jiangshan <jiangshan.ljs@antgroup.com>
> 
> When the arch code provides HAVE_PCPU_RCU_PREEMPT_COUNT and the
> corresponding functions, rcu_preempt core uses the functions to
> implement rcu_read_[un]lock, rcu_preempt_depth(), special bits,
> switching and so on.

The changelogs don't explain the reason for all of that. I'm guessing
from the cover letter that the purpose is to save some instructions on
calls to rcu_read_unlock() due to inline calls and per CPU optimized
instructions but it's hard to guess from the actual individual patches,
which are meants to be the actual git records.

Thanks.

  reply	other threads:[~2024-04-22 10:41 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-28  7:53 [PATCH 00/10] rcu/x86: Use per-cpu rcu preempt count Lai Jiangshan
2024-03-28  7:53 ` [PATCH 01/10] lib: Use rcu_preempt_depth() to replace current->rcu_read_lock_nesting Lai Jiangshan
2024-03-28  7:53 ` [PATCH 02/10] rcu: Move rcu_preempt_depth_set() to rcupdate.h Lai Jiangshan
2024-03-31 11:09   ` Joel Fernandes
2024-03-31 16:16     ` Lai Jiangshan
2024-04-01  2:27       ` Joel Fernandes
2024-04-01 11:40       ` Alan Huang
2024-04-01 11:57         ` Alan Huang
2024-03-28  7:53 ` [PATCH 03/10] rcu: Reorder tree_exp.h after tree_plugin.h Lai Jiangshan
2024-03-28  7:53 ` [PATCH 04/10] rcu: Add macros set_rcu_preempt_special() and clear_rcu_preempt_special() Lai Jiangshan
2024-03-28  7:53 ` [PATCH 05/10] rcu: Make rcu_read_unlock_special() global Lai Jiangshan
2024-03-28  7:53 ` [PATCH 06/10] rcu: Rename marco __LINUX_RCU_H to __KERNEL_RCU_H Lai Jiangshan
2024-03-28  7:53 ` [PATCH 07/10] sched/core: Add rcu_preempt_switch() Lai Jiangshan
2024-03-28  7:53 ` [PATCH 08/10] rcu: Implement PCPU_RCU_PREEMPT_COUNT framework Lai Jiangshan
2024-04-22 10:41   ` Frederic Weisbecker [this message]
2024-03-28  7:53 ` [PATCH 09/10] x86/rcu: Add rcu_preempt_count Lai Jiangshan
2024-03-29  7:37   ` kernel test robot
2024-03-29  7:48   ` kernel test robot
2024-04-22 11:05   ` Frederic Weisbecker
2024-04-23  9:02     ` Lai Jiangshan
2024-04-23 11:33       ` Frederic Weisbecker
2024-03-28  7:53 ` [PATCH 10/10] x86/rcu: Add THUNK rcu_read_unlock_special_thunk Lai Jiangshan
2024-03-29 14:46   ` kernel test robot

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