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From: Andy Tang <andy.tang@nxp.com>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: "rjw@rjwysocki.net" <rjw@rjwysocki.net>,
	"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>
Subject: RE: [EXT] Re: Ask for help about cpufreq issue
Date: Wed, 12 Feb 2020 10:11:43 +0000	[thread overview]
Message-ID: <VI1PR04MB43334811F21E85BD9DACE259F31B0@VI1PR04MB4333.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <20200211063439.aqc4h6np3wjpsg2j@vireshk-i7>

Hi Viresh,

I have another cpufreq issue on our lx2160a platform which has 16 cores and 8 clusters.

Cpufreq works well for ondemand, performance governor. 
But for conservative governor, even though cpu usage is almost zero, but some cpus are not
work on the lowest frequency sometimes. It keeps bouncing from the lowest frequency
to the other higher frequencies. 
The defaut values are used for the tunable for conservative governor.
In summary, why cpu doesn't work at the lowest frequency even the cpu load is almost zero?

root@lx2160ardb:/sys/devices/system/cpu# cat cpufreq/conservative/ 
down_threshold        freq_step             ignore_nice_load      sampling_down_factor  sampling_rate         up_threshold          
root@lx2160ardb:/sys/devices/system/cpu# cat cpufreq/conservative/*
20
5
0
1
8000
80

root@lx2160ardb:/sys/devices/system/cpu# cat cpu[0-9]/cpufreq/scaling_governor
conservative
conservative
conservative
conservative
conservative
conservative
conservative
conservative
conservative
conservative

root@lx2160ardb:/sys/devices/system/cpu# cat cpu[0-9]/cpufreq/scaling_cur_freq
1000000
1000000
1000000
1000000
1000000
1000000
2000000		/// this is not working at the lowest frequency
2000000
700000
700000

Could you please instruct me how to debug this issue?
Thanks,

BR,
Andy
> -----Original Message-----
> From: Viresh Kumar <viresh.kumar@linaro.org>
> Sent: 2020年2月11日 14:35
> To: Andy Tang <andy.tang@nxp.com>
> Cc: rjw@rjwysocki.net; linux-pm@vger.kernel.org
> Subject: Re: [EXT] Re: Ask for help about cpufreq issue
> 
> Caution: EXT Email
> 
> On 11-02-20, 06:23, Andy Tang wrote:
> > I am going to track to dev_pm_qos_add_request() as you suggested.
> > Before that, I am also wondering what the factor it could be to limit the cpu
> max frequency?
> 
> One of them is thermal, but there can be others as well. Just do following
> search in your kernel source code:
> 
> git grep freq_qos_add_request
> 
> This will list all the sources of this constraint.
> 
> --
> viresh

  parent reply	other threads:[~2020-02-12 10:11 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-07  5:09 Ask for help about cpufreq issue Andy Tang
2020-02-07  5:23 ` Viresh Kumar
2020-02-07  6:03   ` [EXT] " Andy Tang
2020-02-07  7:05     ` Viresh Kumar
2020-02-11  4:20       ` Andy Tang
2020-02-11  5:53         ` Viresh Kumar
2020-02-11  6:23           ` Andy Tang
2020-02-11  6:34             ` Viresh Kumar
2020-02-11  7:20               ` Andy Tang
2020-02-12 10:11               ` Andy Tang [this message]
2020-02-12 11:50                 ` Viresh Kumar
2020-02-13  8:18                   ` Andy Tang
2020-02-13  8:48                     ` Viresh Kumar
2020-02-13  9:12                       ` Andy Tang
2020-02-13  9:15                         ` Viresh Kumar
2020-02-13  9:21                           ` Andy Tang
2020-02-14 10:00                       ` Andy Tang
2020-02-17  8:22                         ` Viresh Kumar

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