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Date: Thu, 19 Sep 2024 07:14:59 -0700
From: Christoph Hellwig <hch@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Boqun Feng <boqun.feng@gmail.com>, linux-kernel@vger.kernel.org,
	rcu@vger.kernel.org, linux-mm@kvack.org, lkmm@vger.kernel.org,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	Neeraj Upadhyay <neeraj.upadhyay@kernel.org>,
	Joel Fernandes <joel@joelfernandes.org>,
	Josh Triplett <josh@joshtriplett.org>,
	Uladzislau Rezki <urezki@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	Zqiang <qiang.zhang1211@gmail.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
	Waiman Long <longman@redhat.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Kent Overstreet <kent.overstreet@gmail.com>,
	Vlastimil Babka <vbabka@suse.cz>, maged.michael@gmail.com
Subject: Re: [RFC PATCH 0/4] Add hazard pointers to kernel
Message-ID: <Zuwx409kgivi1G5T@infradead.org>
References: <20240917143402.930114-1-boqun.feng@gmail.com>
 <CAHk-=wi76E2xxvOaZtgN2FK9YKmbK1ru_1atL8eBCs34z7UigA@mail.gmail.com>
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On Wed, Sep 18, 2024 at 09:18:43AM +0200, Linus Torvalds wrote:
> On Tue, 17 Sept 2024 at 16:34, Boqun Feng <boqun.feng@gmail.com> wrote:
> >
> > This series introduces hazard pointers [1] to kernel space. A TL;DR
> > description of hazard pointers is "a scalable refcounting mechanim
> > with RCU-like API". More information can be found at [2].
> 
> Please give actual "this is useful for X, and here is an actual real
> load with numbers showing why it matters".

Agreed.  From the description this would seem like a good fit for
q_usage_counter in the block layer, which currently makes creative use
of percpu counters.