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Date: Thu, 28 May 2026 14:14:08 +0200
From: Frederic Weisbecker <frederic@kernel.org>
To: Puranjay Mohan <puranjay@kernel.org>
Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-trace-kernel@vger.kernel.org,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Neeraj Upadhyay <neeraj.upadhyay@kernel.org>,
	Joel Fernandes <joelagnelf@nvidia.com>,
	Josh Triplett <josh@joshtriplett.org>,
	Boqun Feng <boqun@kernel.org>, Uladzislau Rezki <urezki@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	Zqiang <qiang.zhang@linux.dev>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Davidlohr Bueso <dave@stgolabs.net>
Subject: Re: [RFC PATCH 00/10] RCU: Enable callbacks to benefit from
 expedited grace periods
Message-ID: <ahgxkIbBLkTJyUVt@localhost.localdomain>
References: <20260417231203.785172-1-puranjay@kernel.org>
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In-Reply-To: <20260417231203.785172-1-puranjay@kernel.org>

Hi,

Le Fri, Apr 17, 2026 at 04:11:48PM -0700, Puranjay Mohan a écrit :
> RCU callbacks only track normal grace period sequence numbers. This
> means callbacks must wait for normal GPs even when expedited GPs have
> already elapsed.
> 
> This series tracks both normal and expedited GP sequences in the
> callback infrastructure using struct rcu_gp_oldstate, so callbacks
> advance when either GP type completes.

What is the motivation behind this? When most callbacks don't have much latency
requirements between queue and invocation?

Thanks.

-- 
Frederic Weisbecker
SUSE Labs