linux-kernel - Re: [PATCH v4 1/2] of: cache phandle nodes to reduce cost of of_find_node_by

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Message-ID: <CAHp75Vc4jbJqM0=Yy-1SY6E2WhzHOAAcrn1+KE-jT7MWPtWPpA@mail.gmail.com>
Date:   Wed, 28 Feb 2018 22:19:08 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Frank Rowand <frowand.list@...il.com>
Cc:     Rob Herring <robh+dt@...nel.org>, cpandya@...eaurora.org,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 1/2] of: cache phandle nodes to reduce cost of of_find_node_by_phandle()

On Wed, Feb 28, 2018 at 9:44 PM, Frank Rowand <frowand.list@...il.com> wrote:
> On 02/28/18 11:31, Andy Shevchenko wrote:
>> On Wed, Feb 28, 2018 at 9:04 PM,  <frowand.list@...il.com> wrote:

>> The question is why O(1) is so important? O(log(n)) wouldn't work?
>
> O(1) is not critical.  It was just a nice side result.
>
>
>> Using radix_tree() I suppose allows to dynamically extend or shrink
>> the cache which would work with DT overlays.
>
> The memory usage of the phandle cache in this patch is fairly small.
> The memory overhead of a radix_tree() would not be justified.

OTOH the advantage I mentioned isn't a good argument?

-- 
With Best Regards,
Andy Shevchenko