From: Viresh Kumar <viresh.kumar@linaro.org>
To: Andy Tang <andy.tang@nxp.com>
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: Thu, 13 Feb 2020 14:18:19 +0530 [thread overview]
Message-ID: <20200213084819.jveurrsvtv72ssug@vireshk-i7> (raw)
In-Reply-To: <VI1PR04MB43332FB8B9FAD91160D91A0CF31A0@VI1PR04MB4333.eurprd04.prod.outlook.com>
On 13-02-20, 08:18, Andy Tang wrote:
> I keep monitoring cpu usage for several minutes, by top and mpstat tool, and found
> most of the cpus are 100% idle, once in a while one of the cpus increases the load to about 18%.
I don't think top will be a good way for doing this test as we are
talking about load on a CPU in interval in milliseconds. Please check
with tracing and see what's keeping the CPU busy..
> Technically if the cpu usage is not more than up_threshold(80), cpu won't increase its frequency and keep
> at the lowest frequency when cpu is at the lowest frequency and conservative governor is used.
I agree. Which means that there are some spikes of work getting
scheduled on CPUs. The load will increase slowly and will also
decrease slowly (step-by-step) with conservative governor.
> So I can't understand why cpu frequency increased?
Tracing or debugging cs_dbs_update() in conservative governor is the
only way out I would suggest.
--
viresh
next prev parent reply other threads:[~2020-02-13 8:48 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
2020-02-12 11:50 ` Viresh Kumar
2020-02-13 8:18 ` Andy Tang
2020-02-13 8:48 ` Viresh Kumar [this message]
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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