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ondemand: add a check to avoid negative load calculation

PATCH New Venki Pallipadi 1 participant 1 message Jun 20, 2007 CPU frequency scaling framework

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Venki Pallipadi

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PATCH 1/1 ondemand: add a check to avoid negative load calculation

Due to rounding and inexact jiffy accounting, idle_ticks can sometimes be higher than total_ticks. Make sure those cases are handled as zero load case.

Signed-off-by Venkatesh Pallipadi <[email protected]>
drivers/cpufreq/cpufreq_ondemand.c +3 -2
Index: linux-2.6.22-rc-mm/drivers/cpufreq/cpufreq_ondemand.c
===================================================================
@@ -325,7 +325,7 @@ static struct attribute_group dbs_attr_g
 static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
 {
 	unsigned int idle_ticks, total_ticks;
-	unsigned int load;
+	unsigned int load = 0;
 	cputime64_t cur_jiffies;
 
 	struct cpufreq_policy *policy;

@@ -370,7 +370,8 @@ static void dbs_check_cpu(struct cpu_dbs
 		if (tmp_idle_ticks < idle_ticks)
 			idle_ticks = tmp_idle_ticks;
 	}
-	load = (100 * (total_ticks - idle_ticks)) / total_ticks;
+	if (likely(total_ticks > idle_ticks))
+		load = (100 * (total_ticks - idle_ticks)) / total_ticks;
 
 	/* Check for frequency increase */
 	if (load > dbs_tuners_ins.up_threshold) {