linux-kernel - Re: [PATCH 3/8] sparc: prom: use property "name" directly to construct node names

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Message-Id: <20181109.163211.1071335811309003117.davem@davemloft.net>
Date:   Fri, 09 Nov 2018 16:32:11 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     robh@...nel.org
Cc:     frowand.list@...il.com, linux-kernel@...r.kernel.org,
        sparclinux@...r.kernel.org
Subject: Re: [PATCH 3/8] sparc: prom: use property "name" directly to
 construct node names

From: Rob Herring <robh@...nel.org>
Date: Fri, 9 Nov 2018 07:02:46 -0600

> On Thu, Nov 8, 2018 at 9:13 PM David Miller <davem@...emloft.net> wrote:
>>
>> From: Rob Herring <robh@...nel.org>
>> Date: Wed,  7 Nov 2018 16:31:46 -0600
>>
>> > In preparation to remove direct accesses to the device_node.name
>> > pointer, retrieve the node name from the "name" property instead.
>> >
>> > Cc: "David S. Miller" <davem@...emloft.net>
>> > Cc: sparclinux@...r.kernel.org
>> > Signed-off-by: Rob Herring <robh@...nel.org>
>>
>> On some 32-bit sparcs, the OF runs in non-cached memory.
>>
>> Sucking in the OF device tree take a signficant amount of the
>> boot time on such systems.
>>
>> And these changes are going to make it even slower.
>>
>> Please just put a wrapper around dp->name or whatever and use that,
>> instead of making more get property OF calls which can be very
>> expensive.
> 
> It's not making calls into OF. It is retrieving the property from the
> kernel's copy of the DT (allocated by memblock). So the only
> difference is we have to walk the struct property list to find "name".
> That's perhaps offset by the fact that we'll be doing one less
> property retrieval from OF when this is all done. Right now, we
> retrieve "name" from OF twice per node.

Ok, now I understand, thanks.