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authorVenki Pallipadi <venkatesh.pallipadi@intel.com>2007-06-20 14:26:24 -0700
committerWilly Tarreau <w@1wt.eu>2007-08-25 17:24:21 +0200
commitf06ce2d4e4cbcfed29967c3c9fc40d2ecbc615c6 (patch)
treef379196902f65d6f9c8d38dcf9ac474da78d496d
parentf327bcd16db3128a6c1885e03109361e167d1a56 (diff)
[PATCH] CPUFREQ: ondemand: fix tickless accounting and software coordination bug
With tickless kernel and software coordination os P-states, ondemand can look at wrong idle statistics. This can happen when ondemand sampling is happening on CPU 0 and due to software coordination sampling also looks at utilization of CPU 1. If CPU 1 is in tickless state at that moment, its idle statistics will not be uptodate and CPU 0 thinks CPU 1 is idle for less amount of time than it actually is. This can be resolved by looking at all the busy times of CPUs, which is accurate, even with tickless, and use that to determine idle time in a round about way (total time - busy time). Thanks to Arjan for originally reporting the ondemand bug on Lenovo T61. Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Dave Jones <davej@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Willy Tarreau <w@1wt.eu>
-rw-r--r--drivers/cpufreq/cpufreq_ondemand.c25
1 files changed, 18 insertions, 7 deletions
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index f697449327c6..3bfaeb577624 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -95,15 +95,25 @@ static struct dbs_tuners {
static inline cputime64_t get_cpu_idle_time(unsigned int cpu)
{
- cputime64_t retval;
+ cputime64_t idle_time;
+ cputime64_t cur_jiffies;
+ cputime64_t busy_time;
- retval = cputime64_add(kstat_cpu(cpu).cpustat.idle,
- kstat_cpu(cpu).cpustat.iowait);
+ cur_jiffies = jiffies64_to_cputime64(get_jiffies_64());
+ busy_time = cputime64_add(kstat_cpu(cpu).cpustat.user,
+ kstat_cpu(cpu).cpustat.system);
- if (dbs_tuners_ins.ignore_nice)
- retval = cputime64_add(retval, kstat_cpu(cpu).cpustat.nice);
+ busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.irq);
+ busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.softirq);
+ busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.steal);
- return retval;
+ if (!dbs_tuners_ins.ignore_nice) {
+ busy_time = cputime64_add(busy_time,
+ kstat_cpu(cpu).cpustat.nice);
+ }
+
+ idle_time = cputime64_sub(cur_jiffies, busy_time);
+ return idle_time;
}
/*
@@ -338,7 +348,8 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
cur_jiffies = jiffies64_to_cputime64(get_jiffies_64());
total_ticks = (unsigned int) cputime64_sub(cur_jiffies,
this_dbs_info->prev_cpu_wall);
- this_dbs_info->prev_cpu_wall = cur_jiffies;
+ this_dbs_info->prev_cpu_wall = get_jiffies_64();
+
if (!total_ticks)
return;
/*