cpufreq: Xen support for the ondemand governor in Linux dom0

Modify the cpufreq ondemand governor so that it can get idle and
total nsecs from the Xen hypervisor. Xen uses nsecs to measure
idle time, while Linux uses ticks.  Other than accounting for
that difference, use the same algorithm to calculate idle time.

Signed-off-by: Mark Langsdorf <mark.langsdorf@amd.com>

diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index 52cf1f02182591f64f527144e1e3a1394ee9a050..a1ca3cb26f78ea6c18fc1ae5837fdb44cce6bd1c 100644 (file)
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -222,17 +222,14 @@ static struct attribute_group dbs_attr_group = {
 
 /************************** sysfs end ************************/
 
-static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
+#ifndef CONFIG_XEN
+static int dbs_calc_load(struct cpu_dbs_info_s *this_dbs_info)
 {
-       unsigned int idle_ticks, total_ticks;
-       unsigned int load;
-       cputime64_t cur_jiffies;
-
        struct cpufreq_policy *policy;
+       cputime64_t cur_jiffies;
+       cputime64_t total_ticks, idle_ticks;
        unsigned int j;
-
-       if (!this_dbs_info->enable)
-               return;
+       int load;
 
        policy = this_dbs_info->cur_policy;
        cur_jiffies = jiffies64_to_cputime64(get_jiffies_64());
@@ -240,7 +237,7 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
                        this_dbs_info->prev_cpu_wall);
        this_dbs_info->prev_cpu_wall = cur_jiffies;
        if (!total_ticks)
-               return;
+               return 200;
        /*
         * Every sampling_rate, we check, if current idle time is less
         * than 20% (default), then we try to increase frequency
@@ -270,6 +267,70 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
                        idle_ticks = tmp_idle_ticks;
        }
        load = (100 * (total_ticks - idle_ticks)) / total_ticks;
+       return load;
+}
+#else
+
+#include <xen/interface/platform.h>
+static int dbs_calc_load(struct cpu_dbs_info_s *this_dbs_info)
+{
+       int load = 0;
+       struct xen_platform_op op;
+       uint64_t idletime[NR_CPUS];
+       struct cpufreq_policy *policy;
+       unsigned int j;
+       cpumask_t cpumap;
+
+       op.cmd = XENPF_getidletime;
+       set_xen_guest_handle(op.u.getidletime.cpumap_bitmap, (uint8_t *) cpus_addr(cpumap));
+       op.u.getidletime.cpumap_nr_cpus = NR_CPUS;// num_online_cpus();
+       set_xen_guest_handle(op.u.getidletime.idletime, idletime);
+       if (HYPERVISOR_platform_op(&op))
+               return 200;
+
+       policy = this_dbs_info->cur_policy;
+       cpumap = policy->cpus;
+       for_each_cpu_mask(j, cpumap) {
+               cputime64_t total_idle_nsecs, tmp_idle_nsecs;
+               cputime64_t total_wall_nsecs, tmp_wall_nsecs;
+               struct cpu_dbs_info_s *j_dbs_info;
+               unsigned long tmp_load;
+
+               j_dbs_info = &per_cpu(cpu_dbs_info, j);
+               total_idle_nsecs = idletime[j];
+               tmp_idle_nsecs = cputime64_sub(total_idle_nsecs,
+                               j_dbs_info->prev_cpu_idle);
+               total_wall_nsecs = op.u.getidletime.now;
+               tmp_wall_nsecs = cputime64_sub(total_wall_nsecs,
+                               j_dbs_info->prev_cpu_wall);
+
+               if (tmp_wall_nsecs == 0)
+                       return 200;
+
+               j_dbs_info->prev_cpu_wall = total_wall_nsecs;
+               j_dbs_info->prev_cpu_idle = total_idle_nsecs;
+
+               tmp_load = (100 * (tmp_wall_nsecs - tmp_idle_nsecs)) /
+                               tmp_wall_nsecs;
+               load = max(load, min(100, (int) tmp_load));
+       }
+       return load;
+}
+#endif
+
+static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
+{
+       int load;
+
+       struct cpufreq_policy *policy;
+
+       if (!this_dbs_info->enable)
+               return;
+
+       policy = this_dbs_info->cur_policy;
+       load = dbs_calc_load(this_dbs_info);
+       if (load > 100) 
+               return;
 
        /* Check for frequency increase */
        if (load > dbs_tuners_ins.up_threshold) {