examples/vm_power: fix OOB frequency oscillations

[dpdk.git] / examples / vm_power_manager / oob_monitor_x86.c

diff --git a/examples/vm_power_manager/oob_monitor_x86.c b/examples/vm_power_manager/oob_monitor_x86.c
index ebd96b2..aecfcb2 100644 (file)
--- a/examples/vm_power_manager/oob_monitor_x86.c
+++ b/examples/vm_power_manager/oob_monitor_x86.c
@@ -39,6 +39,7 @@ apply_policy(int core)
        int64_t hits_diff, miss_diff;
        float ratio;
        int ret;
+       int freq_window_idx, up_count = 0, i;
 
        g_active = 0;
        ci = get_core_info();
@@ -101,10 +102,37 @@ apply_policy(int core)
 
        ratio = (float)miss_diff * (float)100 / (float)hits_diff;
 
-       if (ratio < ci->branch_ratio_threshold)
-               power_manager_scale_core_min(core);
+       /*
+        * Store the last few directions that the ratio indicates
+        * we should take. If there's on 'up', then we scale up
+        * quickly. If all indicate 'down', only then do we scale
+        * down. Each core_details struct has it's own array.
+        */
+       freq_window_idx = ci->cd[core].freq_window_idx;
+       if (ratio > ci->branch_ratio_threshold)
+               ci->cd[core].freq_directions[freq_window_idx] = 1;
        else
-               power_manager_scale_core_max(core);
+               ci->cd[core].freq_directions[freq_window_idx] = 0;
+
+       freq_window_idx++;
+       freq_window_idx = freq_window_idx & (FREQ_WINDOW_SIZE-1);
+       ci->cd[core].freq_window_idx = freq_window_idx;
+
+       up_count = 0;
+       for (i = 0; i < FREQ_WINDOW_SIZE; i++)
+               up_count +=  ci->cd[core].freq_directions[i];
+
+       if (up_count == 0) {
+               if (ci->cd[core].freq_state != FREQ_MIN) {
+                       power_manager_scale_core_min(core);
+                       ci->cd[core].freq_state = FREQ_MIN;
+               }
+       } else {
+               if (ci->cd[core].freq_state != FREQ_MAX) {
+                       power_manager_scale_core_max(core);
+                       ci->cd[core].freq_state = FREQ_MAX;
+               }
+       }
 
        g_active = 1;
        return ratio;