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Message-ID: <5bd5ee4a-710a-96bc-abe8-772b2e60f478@efficios.com>
Date: Tue, 20 Dec 2022 14:01:30 -0500
From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To: Joel Fernandes <joel@...lfernandes.org>
Cc: linux-kernel@...r.kernel.org,
Josh Triplett <josh@...htriplett.org>,
Lai Jiangshan <jiangshanlai@...il.com>,
"Paul E. McKenney" <paulmck@...nel.org>, rcu@...r.kernel.org,
Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [RFC 0/2] srcu: Remove pre-flip memory barrier
On 2022-12-20 13:29, Joel Fernandes wrote:
>
> I do want to finish my memory barrier studies of SRCU over the holidays since I have been deep in the hole with that already. Back to the post flip memory barrier here since I think now even that might not be needed…
I strongly suspect the memory barrier after flip is useless for the same
reasons I mentioned explaining why the barrier before the flip is useless.
However, we need to double-check that we have memory barriers at the
beginning and end of synchronize_srcu, and between load of "unlock"
counters and load of "lock" counters.
Where is the barrier at the beginning of synchronize_srcu ?
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com
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