linux-kernel - Re: [PATCH 1/2] memory: samsung: exynos5422-dmc: Adjust polling interval and uptreshold

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Date:   Fri, 10 Jul 2020 13:56:33 +0100
From:   Lukasz Luba <lukasz.luba@....com>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     Chanwoo Choi <cw00.choi@...sung.com>, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, willy.mh.wolff.ml@...il.com,
        k.konieczny@...sung.com, b.zolnierkie@...sung.com,
        chanwoo@...nel.org, myungjoo.ham@...sung.com,
        kyungmin.park@...sung.com, s.nawrocki@...sung.com, kgene@...nel.org
Subject: Re: [PATCH 1/2] memory: samsung: exynos5422-dmc: Adjust polling
 interval and uptreshold



On 7/10/20 1:45 PM, Krzysztof Kozlowski wrote:
> On Fri, Jul 10, 2020 at 09:34:45AM +0100, Lukasz Luba wrote:
>> Hi Chanwoo,
>>
>> On 7/9/20 5:08 AM, Chanwoo Choi wrote:
>>> Hi Lukasz,
>>>
>>> On 7/9/20 12:34 AM, Lukasz Luba wrote:
>>>> In order to react faster and make better decisions under some workloads,
>>>> benchmarking the memory subsystem behavior, adjust the polling interval
>>>> and upthreshold value used by the simple_ondemand governor.
>>>>
>>>> Reported-by: Willy Wolff <willy.mh.wolff.ml@...il.com>
>>>> Signed-off-by: Lukasz Luba <lukasz.luba@....com>
>>>> ---
>>>>    drivers/memory/samsung/exynos5422-dmc.c | 4 ++--
>>>>    1 file changed, 2 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/memory/samsung/exynos5422-dmc.c b/drivers/memory/samsung/exynos5422-dmc.c
>>>> index 93e9c2429c0d..e03ee35f0ab5 100644
>>>> --- a/drivers/memory/samsung/exynos5422-dmc.c
>>>> +++ b/drivers/memory/samsung/exynos5422-dmc.c
>>>> @@ -1466,10 +1466,10 @@ static int exynos5_dmc_probe(struct platform_device *pdev)
>>>>    		 * Setup default thresholds for the devfreq governor.
>>>>    		 * The values are chosen based on experiments.
>>>>    		 */
>>>> -		dmc->gov_data.upthreshold = 30;
>>>> +		dmc->gov_data.upthreshold = 10;
>>>>    		dmc->gov_data.downdifferential = 5;
>>>> -		exynos5_dmc_df_profile.polling_ms = 500;
>>>> +		exynos5_dmc_df_profile.polling_ms = 100;
>>>>    	}
>>>>
>>>
>>> Reviewed-by: Chanwoo Choi <cw00.choi@...sung.com>
>>>
>>
>> Thank you for the review. Do you think this patch could go through
>> your tree together with your patches?
>>
>> I don't know Krzysztof's opinion about the patch 2/2, but
>> I would expect, assuming the patch itself is correct, he would
>> like to take it into his next/dt branch.
> 
> In the cover letter you mentioned that this is a follow up for the
> Chanwoo's patchset. But are these patches really depending on it? Can
> they be picked up independently?


They are not heavily dependent on Chanwoo's patches.
Yes, they can be picked up independently.
I just wanted to mention that the patch 1/2 was produced on the
code base which had already applied Chanwoo's patch for DMC.
If you like to take both 1/2 and 2/2 into your tree, it's good.

Thank you for having a look on this.

Regards,
Lukasz


> 
> The DTS patch must go through arm soc, so I will take it. If it really
> depends on driver changes, then it has to wait for next release.
> 
> Best regards,
> Krzysztof
>