linux-kernel - Re: [TEGRA194_CPUFREQ Patch 2/3] cpufreq: Add Tegra194 cpufreq driver

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Message-ID: <d6e0eed6-4267-fca9-59e1-02d16e17ff34@nvidia.com>
Date:   Wed, 15 Apr 2020 16:55:53 +0530
From:   Sumit Gupta <sumitg@...dia.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
CC:     <rjw@...ysocki.net>, <catalin.marinas@....com>, <will@...nel.org>,
        <thierry.reding@...il.com>, <jonathanh@...dia.com>,
        <talho@...dia.com>, <linux-pm@...r.kernel.org>,
        <linux-tegra@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <bbasu@...dia.com>,
        <mperttunen@...dia.com>
Subject: Re: [TEGRA194_CPUFREQ Patch 2/3] cpufreq: Add Tegra194 cpufreq driver



On 14/04/20 11:15 AM, Viresh Kumar wrote:
> External email: Use caution opening links or attachments
> 
> 
> On 13-04-20, 17:50, Sumit Gupta wrote:
>> This was done considering long delay value as explained previously.
>> Do you think that smp_call_function_single() would be better than work queue
>> here?
> 
> Don't work with assumptions, you should test both and see which one
> works better. Workqueue should never be faster than
> smp_call_function_single() with my understanding.
Checked the time taken and its almost same in both cases.
Earlier we used smp_call_function_single(), but delay time period was 
small in that SOC. In T194, the time period was more. So, this is an 
optimization done because using work queue has advantage as interrupts 
will not be disabled for that period.
If you think work queue is not required, then can remove it. The 
functionality works fine in both cases.

> 
> --
> viresh
>