X-Git-Url: http://git.droids-corp.org/?a=blobdiff_plain;f=examples%2Fvm_power_manager%2Foob_monitor_x86.c;h=a5b1c168c3c86cefa05253ef886881e00edbfc24;hb=0a65bf8d4124866678f3ddb816d36aae66f791eb;hp=589c604e5c6c4214fef72ed9bc65fcd7dc931b3e;hpb=711f43ba568acadf6cbccb9f8a29abf0fb3baa25;p=dpdk.git

diff --git a/examples/vm_power_manager/oob_monitor_x86.c b/examples/vm_power_manager/oob_monitor_x86.c
index 589c604e5c..a5b1c168c3 100644
--- a/examples/vm_power_manager/oob_monitor_x86.c
+++ b/examples/vm_power_manager/oob_monitor_x86.c
@@ -33,12 +33,13 @@ static float
 apply_policy(int core)
 {
 	struct core_info *ci;
-	uint64_t counter;
+	uint64_t counter = 0;
 	uint64_t branches, branch_misses;
-	uint32_t last_branches, last_branch_misses;
-	int hits_diff, miss_diff;
+	uint64_t last_branches, last_branch_misses;
+	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();
@@ -54,6 +55,7 @@ apply_policy(int core)
 				core);
 	branches = counter;
 
+	counter = 0;
 	ret = pread(ci->cd[core].msr_fd, &counter,
 			sizeof(counter), IA32_PERFCTR1);
 	if (ret < 0)
@@ -66,13 +68,25 @@ apply_policy(int core)
 	ci->cd[core].last_branches = branches;
 	ci->cd[core].last_branch_misses = branch_misses;
 
-	hits_diff = (int)branches - (int)last_branches;
+	/*
+	 * Intentional right shift to make MSB 0 to avoid
+	 * possible signed overflow or truncation.
+	 */
+	branches >>= 1;
+	last_branches >>= 1;
+	hits_diff = (int64_t)branches - (int64_t)last_branches;
 	if (hits_diff <= 0) {
 		/* Likely a counter overflow condition, skip this round */
 		return -1.0;
 	}
 
-	miss_diff = (int)branch_misses - (int)last_branch_misses;
+	/*
+	 * Intentional right shift to make MSB 0 to avoid
+	 * possible signed overflow or truncation.
+	 */
+	branch_misses >>= 1;
+	last_branch_misses >>= 1;
+	miss_diff = (int64_t)branch_misses - (int64_t)last_branch_misses;
 	if (miss_diff <= 0) {
 		/* Likely a counter overflow condition, skip this round */
 		return -1.0;
@@ -82,16 +96,43 @@ apply_policy(int core)
 	g_branch_misses = miss_diff;
 
 	if (hits_diff < (INTERVAL*100)) {
-		/* Likely no workload running on this core. Skip. */
-		return -1.0;
+		/* Likely no workload running on this core. */
+		ratio = 0.0;
+	} else {
+		ratio = (float)miss_diff * (float)100 / (float)hits_diff;
 	}
 
-	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->cd[core].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;