linux-kernel - Re: [PATCH] cpufreq: governor: Be friendly towards latency-sensitive bursty workloads

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Date:	Tue, 3 Jun 2014 15:09:19 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
	"ego@...ux.vnet.ibm.com" <ego@...ux.vnet.ibm.com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cpufreq: governor: Be friendly towards latency-sensitive
 bursty workloads

On 3 June 2014 15:02, Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com> wrote:
> diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
> index e1c6433..3e8588f 100644
> --- a/drivers/cpufreq/cpufreq_governor.c
> +++ b/drivers/cpufreq/cpufreq_governor.c
> @@ -36,14 +36,29 @@ void dbs_check_cpu(struct dbs_data *dbs_data, int cpu)
>         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
>         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
>         struct cpufreq_policy *policy;
> +       unsigned int sampling_rate;
>         unsigned int max_load = 0;
>         unsigned int ignore_nice;
>         unsigned int j;
>
> -       if (dbs_data->cdata->governor == GOV_ONDEMAND)
> +       if (dbs_data->cdata->governor == GOV_ONDEMAND) {
> +               struct od_cpu_dbs_info_s *od_dbs_info;
> +
> +               /*
> +                * Sometimes, the ondemand governor uses an additional
> +                * multiplier to give long delays. So apply this multiplier to
> +                * the 'sampling_rate', so as to keep the wake-up-from-idle
> +                * detection logic a bit conservative.
> +                */
> +               sampling_rate = od_tuners->sampling_rate;
> +               od_dbs_info = dbs_data->cdata->get_cpu_dbs_info_s(cpu);

Probably do both above right after definition of od_dbs_info or merge
above with it. and just keep below after the comment ?

> +               sampling_rate *= od_dbs_info->rate_mult;
--
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