[Xen-changelog] [linux-2.6.18-xen] cpufreq: Xen support for the ondemand governor in Linux dom0

["Xen patchbot-linux-2.6.18-xen" <patchbot-linux-2.6.18-xen@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir@xxxxxxxxxxxxx>
# Date 1193679813 0
# Node ID 7aaec9c0a2137fc3d449be5a99a5b5fbd0cd7808
# Parent  e9cb774f0bd9019794e22e63d2e25ee758ab3433
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@xxxxxxx>
---
 drivers/cpufreq/cpufreq_ondemand.c |   81 ++++++++++++++++++++++++++++++++-----
 1 files changed, 71 insertions(+), 10 deletions(-)

diff -r e9cb774f0bd9 -r 7aaec9c0a213 drivers/cpufreq/cpufreq_ondemand.c
--- a/drivers/cpufreq/cpufreq_ondemand.c        Mon Oct 29 17:42:54 2007 +0000
+++ b/drivers/cpufreq/cpufreq_ondemand.c        Mon Oct 29 17:43:33 2007 +0000
@@ -222,17 +222,14 @@ static struct attribute_group dbs_attr_g
 
 /************************** sysfs end ************************/
 
-static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
-{
-       unsigned int idle_ticks, total_ticks;
-       unsigned int load;
+#ifndef CONFIG_XEN
+static int dbs_calc_load(struct cpu_dbs_info_s *this_dbs_info)
+{
+       struct cpufreq_policy *policy;
        cputime64_t cur_jiffies;
-
-       struct cpufreq_policy *policy;
+       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
                        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
                        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) {

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