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[CPUFREQ] ondemand/conservative: sanitize sampling_rate restrictions

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Limit sampling rate to transition_latency * 100 or kernel limits.
If sampling_rate is tried to be set too low, set the lowest allowed value.

Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Dave Jones <davej@redhat.com>
This commit is contained in:
Thomas Renninger
2009-02-04 11:55:12 +01:00
committed by Dave Jones
parent 9411b4ef7f
commit 112124ab0a
3 changed files with 49 additions and 21 deletions
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28
drivers/cpufreq/cpufreq_conservative.c
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@@ -54,8 +54,20 @@ static unsigned int def_sampling_rate;
(MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10))
#define MIN_SAMPLING_RATE \
(def_sampling_rate / MIN_SAMPLING_RATE_RATIO)
/* Above MIN_SAMPLING_RATE will vanish with its sysfs file soon
* Define the minimal settable sampling rate to the greater of:
* - "HW transition latency" * 100 (same as default sampling / 10)
* - MIN_STAT_SAMPLING_RATE
* To avoid that userspace shoots itself.
*/
static unsigned int minimum_sampling_rate(void)
{
return max(def_sampling_rate / 10, MIN_STAT_SAMPLING_RATE);
}
/* This will also vanish soon with removing sampling_rate_max */
#define MAX_SAMPLING_RATE (500 * def_sampling_rate)
#define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER (1000)
#define LATENCY_MULTIPLIER (1000)
#define DEF_SAMPLING_DOWN_FACTOR (1)
#define MAX_SAMPLING_DOWN_FACTOR (10)
#define TRANSITION_LATENCY_LIMIT (10 * 1000 * 1000)
@@ -208,13 +220,11 @@ static ssize_t store_sampling_rate(struct cpufreq_policy *unused,
ret = sscanf(buf, "%u", &input);
mutex_lock(&dbs_mutex);
if (ret != 1 || input > MAX_SAMPLING_RATE ||
input < MIN_SAMPLING_RATE) {
if (ret != 1) {
mutex_unlock(&dbs_mutex);
return -EINVAL;
}
dbs_tuners_ins.sampling_rate = input;
dbs_tuners_ins.sampling_rate = max(input, minimum_sampling_rate());
mutex_unlock(&dbs_mutex);
return count;
@@ -540,11 +550,9 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
if (latency == 0)
latency = 1;
def_sampling_rate = 10 * latency *
DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
if (def_sampling_rate < MIN_STAT_SAMPLING_RATE)
def_sampling_rate = MIN_STAT_SAMPLING_RATE;
def_sampling_rate =
max(10 * latency * LATENCY_MULTIPLIER,
MIN_STAT_SAMPLING_RATE);
dbs_tuners_ins.sampling_rate = def_sampling_rate;