Hi,
The ondemand delay value is calculated before calling dbs_check_cpu
which can lead to a delay value of sampling_rate*sampling_down_factor
but a frequency set to the lowest value. The main result is a slow
responsiveness during this period. This patch moves the calculation of
delay after the call of dbs_check_cpu. I have seen this problem when
testing cpufreq-bench on my Arm platform.
Vincent
On 7 February 2011 17:14, Vincent Guittot <vincent.guittot@xxxxxxxxxx> wrote:
> calculate ondemand delay after dbs_check_cpu call because it can
> modify rate_mult value
>
> use freq_lo_jiffies value for the sub sample period of powersave_bias mode
>
> Signed-off-by: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
> ---
> drivers/cpufreq/cpufreq_ondemand.c | 20 +++++++++++++-------
> 1 files changed, 13 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/cpufreq/cpufreq_ondemand.c
> b/drivers/cpufreq/cpufreq_ondemand.c
> index 58aa85e..44c2dba 100644
> --- a/drivers/cpufreq/cpufreq_ondemand.c
> +++ b/drivers/cpufreq/cpufreq_ondemand.c
> @@ -641,13 +641,7 @@ static void do_dbs_timer(struct work_struct *work)
> container_of(work, struct cpu_dbs_info_s, work.work);
> unsigned int cpu = dbs_info->cpu;
> int sample_type = dbs_info->sample_type;
> -
> - /* We want all CPUs to do sampling nearly on same jiffy */
> - int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate
> - * dbs_info->rate_mult);
> -
> - if (num_online_cpus() > 1)
> - delay -= jiffies % delay;
> + int delay;
>
> mutex_lock(&dbs_info->timer_mutex);
>
> @@ -660,10 +654,22 @@ static void do_dbs_timer(struct work_struct *work)
> /* Setup timer for SUB_SAMPLE */
> dbs_info->sample_type = DBS_SUB_SAMPLE;
> delay = dbs_info->freq_hi_jiffies;
> + } else {
> + /* We want all CPUs to do sampling nearly on
> + * same jiffy
> + */
> + delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate
> + * dbs_info->rate_mult);
> +
> + if (num_online_cpus() > 1)
> + delay -= jiffies % delay;
> +
> }
> +
> } else {
> __cpufreq_driver_target(dbs_info->cur_policy,
> dbs_info->freq_lo, CPUFREQ_RELATION_H);
> + delay = dbs_info->freq_lo_jiffies;
> }
> schedule_delayed_work_on(cpu, &dbs_info->work, delay);
> mutex_unlock(&dbs_info->timer_mutex);
> --
> 1.7.1
>
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