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Date:   Mon, 10 Feb 2020 13:11:57 +0000
From:   Mark Brown <broonie@kernel.org>
To:     Davidlohr Bueso <dave@stgolabs.net>
Cc:     akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
        mcgrof@kernel.org, alex.williamson@redhat.com,
        Davidlohr Bueso <dbueso@suse.de>
Subject: Re: [PATCH 3/5] regmap: optimize sync() and drop() regcache callbacks
Message-ID: <20200210131157.GE7685@sirena.org.uk>
References: <20200207180305.11092-1-dave@stgolabs.net>
 <20200207180305.11092-4-dave@stgolabs.net>
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On Fri, Feb 07, 2020 at 10:03:03AM -0800, Davidlohr Bueso wrote:
> At a higher memory footprint (two additional pointers per node) we
> can get branchless O(1) tree iterators which can optimize in-order
> tree walks/traversals. For example, on my laptop looking at the rbtree
> debugfs entries:

It's not clear that this is a good optimization - we're increasing the
memory footprint for a bit of performance but our performance is all
relative to the I2C or SPI I/O we're most likely all in the noise here
whereas for larger maps the size cost looks like it could be quite bad
(but equally your case looks to have a lot of 2 register blocks which is
almost the worst case for overhead so...).

That said the code is fine so from that point of view:

Acked-by: Mark Brown <broonie@kernel.org>

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