linux-kernel - Re: [PATCH v2] of: use hash based search in of_find_node_by

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Date:   Tue, 30 Jan 2018 10:59:27 -0800
From:   Frank Rowand <frowand.list@...il.com>
To:     Chintan Pandya <cpandya@...eaurora.org>, robh+dt@...nel.org,
        devicetree@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v2] of: use hash based search in of_find_node_by_phandle

On 01/30/18 00:04, Chintan Pandya wrote:
>> (1)
>>
>> Can you point me to the driver code that is invoking
>> the search?
> There are many locations. Few of them being,
> https://source.codeaurora.org/quic/la/kernel/msm-4.9/tree/drivers/of/irq.c?h=msm-4.9#n214
> https://source.codeaurora.org/quic/la/kernel/msm-4.9/tree/drivers/irqchip/irq-gic-v3.c?h=msm-4.9#n1107
> https://source.codeaurora.org/quic/la/kernel/msm-4.9/tree/drivers/clk/msm/msm-clock-controller.c?h=msm-4.9#n492
>>
>> (2)
>>
>> And also the .dts devicetree source file that you are seeing
>> large overhead with.
> SDM670 DTS tree starts here.
> https://source.codeaurora.org/quic/la/kernel/msm-4.9/tree/arch/arm64/boot/dts/qcom/sdm670.dtsi?h=msm-4.9

Thanks, I'm starting to get a picture of what you are facing.

The file you point at is a .dtsi, not a .dts.  There are quite a
few sdm670*.dts files in that tree.  Which one corresponds to
the system you are working on?

I picked a random one (sdm670-cdp.dts), but I need to be looking
at the .dts that you are using to be able to ask reasonable
questions instead of poking around in the dark.

Also, when I clone that git tree there is not a valid HEAD.  I
picked what looked like a reasonable commit to checkout, but I
would prefer to be looking at the same exact source that you
are working with.  Can you give me the commit id  of the branch
that you are working on?

-Frank


>>
>>
>> (3) -- this one is less important, but if the info is easily
>>         available to you
>>
>> Sorry about dribbling out questions instead of all at once....
>>
>> What is the hardware you are testing this on?
> SDM670
>> Processor?
> Kryo-300 Silver
>> Cache size?
> From DT,
> L1 32KB (per CPU)
> L2 128KB (per CPU)
> L3 1MB (total)
>> Memory size?
> 6GB
>> Processor frequency?
> Max 1.7GHz for core 0. Not sure about boot time frequency.
>> Any other attribute of the system that will help me understand
>> the boot performance you are seeing?
> I'm not able to profile of_find_node_by_phandle specifically as timers are
> not up by then. So, just observing overall boot time for comparison.
> 
> My recent results were taken on debug_defconfig which has many performance
> slowing code. So, gap between base-build and w/ the test patches would be
> more than the actual production build.
> 
> Thanks,
> Chintan
>