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Date: Tue, 2 Jan 2024 02:28:04 -0800
From: Christoph Hellwig <hch@infradead.org>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH 4/7] xfs: allow blocking notifier chains with filesystem
 hooks
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On Sun, Dec 31, 2023 at 12:05:29PM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
> 
> Make it so that we can switch between notifier chain implementations for
> testing purposes.  On the author's test system, calling an empty srcu
> notifier chain cost about 19ns per call, vs. 4ns for a blocking notifier
> chain.  Hm.  Might we actually want regular blocking notifiers?

Sounds like it.  But what is important is that we really shouldn't
provide both and punt the decision to the user..