examples/vm_power: make branch ratio threshold per core

This modification allows for the branch ratio threshold to be set
per core rather than system wide. This gives greater flexibility to
the branch ratio monitoring allowing it to manage different
workloads with different characteristics on the same system.

Signed-off-by: Rory Sexton <rory.sexton@intel.com>
Reviewed-by: David Hunt <david.hunt@intel.com>
Acked-by: Reshma Pattan <reshma.pattan@intel.com>

doc/guides/sample_app_ug/vm_power_management.rst

@@ -410,19 +410,19 @@ There are a couple of command line parameters for enabling the out-of-band
 monitoring of branch ratios on cores doing busy polling using PMDs as
 described below:
 
-``--core-list {list of cores}``
+``--core-branch-ratio {list of cores}:{branch ratio for listed cores}``
    Specify the list of cores to monitor the ratio of branch misses
    to branch hits.  A tightly-polling PMD thread has a very low
    branch ratio, therefore the core frequency scales down to the
    minimum allowed value. On receiving packets, the code path changes,
    causing the branch ratio to increase. When the ratio goes above
    the ratio threshold, the core frequency scales up to the maximum
-   allowed value.
+   allowed value. The specified branch-ratio is a floating point number
+   that identifies the threshold at which to scale up or down for the
+   elements of the core-list. If not included the default branch ratio of
+   0.01 but will need adjustment for different workloads
 
-``--branch-ratio {ratio}``
-   Specify a floating-point number that identifies the threshold at which
-   to scale up or down for the given workload. The default branch ratio
-   is 0.01 and needs adjustment for different workloads.
+   This parameter can be used multiple times for different sets of cores.
 
 
 Compiling and Running the Guest Applications

examples/vm_power_manager/main.c

@@ -165,15 +165,14 @@ parse_args(int argc, char **argv)
 	static struct option lgopts[] = {
 		{ "mac-updating", no_argument, 0, 1},
 		{ "no-mac-updating", no_argument, 0, 0},
-		{ "core-list", optional_argument, 0, 'l'},
+		{ "core-branch-ratio", optional_argument, 0, 'b'},
 		{ "port-list", optional_argument, 0, 'p'},
-		{ "branch-ratio", optional_argument, 0, 'b'},
 		{NULL, 0, 0, 0}
 	};
 	argvopt = argv;
 	ci = get_core_info();
 
-	while ((opt = getopt_long(argc, argvopt, "l:p:q:T:b:",
+	while ((opt = getopt_long(argc, argvopt, "p:q:T:b:",
 				  lgopts, &option_index)) != EOF) {
 
 		switch (opt) {
@@ -185,7 +184,8 @@ parse_args(int argc, char **argv)
 				return -1;
 			}
 			break;
-		case 'l':
+		case 'b':
+			branch_ratio = BRANCH_RATIO_THRESHOLD;
 			oob_enable = malloc(ci->core_count * sizeof(uint16_t));
 			if (oob_enable == NULL) {
 				printf("Error - Unable to allocate memory\n");
@@ -193,31 +193,36 @@ parse_args(int argc, char **argv)
 			}
 			cnt = parse_set(optarg, oob_enable, ci->core_count);
 			if (cnt < 0) {
-				printf("Invalid core-list - [%s]\n",
+				printf("Invalid core-list section in "
+				       "core-branch-ratio matrix - [%s]\n",
 						optarg);
 				free(oob_enable);
 				break;
 			}
-			for (i = 0; i < ci->core_count; i++) {
-				if (oob_enable[i]) {
-					printf("***Using core %d\n", i);
-					ci->cd[i].oob_enabled = 1;
-					ci->cd[i].global_enabled_cpus = 1;
-				}
+			cnt = parse_branch_ratio(optarg, &branch_ratio);
+			if (cnt < 0) {
+				printf("Invalid branch-ratio section in "
+				       "core-branch-ratio matrix - [%s]\n",
+						optarg);
+				free(oob_enable);
+				break;
 			}
-			free(oob_enable);
-			break;
-		case 'b':
-			branch_ratio = 0.0;
-			if (strlen(optarg))
-				branch_ratio = atof(optarg);
-			if (branch_ratio <= 0.0) {
+			if (branch_ratio <= 0.0 || branch_ratio > 100.0) {
 				printf("invalid branch ratio specified\n");
 				return -1;
 			}
-			ci->branch_ratio_threshold = branch_ratio;
-			printf("***Setting branch ratio to %f\n",
-					branch_ratio);
+			for (i = 0; i < ci->core_count; i++) {
+				if (oob_enable[i]) {
+					printf("***Using core %d "
+					       "with branch ratio %f\n",
+					       i, branch_ratio);
+					ci->cd[i].oob_enabled = 1;
+					ci->cd[i].global_enabled_cpus = 1;
+					ci->cd[i].branch_ratio_threshold =
+								branch_ratio;
+				}
+			}
+			free(oob_enable);
 			break;
 		/* long options */
 		case 0:

examples/vm_power_manager/oob_monitor_x86.c

@@ -109,7 +109,7 @@ apply_policy(int core)
 	 * 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)
+	if (ratio > ci->cd[core].branch_ratio_threshold)
 		ci->cd[core].freq_directions[freq_window_idx] = 1;
 	else
 		ci->cd[core].freq_directions[freq_window_idx] = 0;

examples/vm_power_manager/parse.c

@@ -60,7 +60,7 @@ parse_set(const char *input, uint16_t set[], unsigned int num)
 				min = idx;
 			else /* avoid continuous '-' */
 				return -1;
-		} else if ((*end == ',') || (*end == '\0')) {
+		} else if ((*end == ',') || (*end == ':') || (*end == '\0')) {
 			max = idx;
 
 			if (min == num)
@@ -75,7 +75,45 @@ parse_set(const char *input, uint16_t set[], unsigned int num)
 			return -1;
 
 		str = end + 1;
-	} while (*end != '\0');
+	} while ((*end != '\0') && (*end != ':'));
+
+	return str - input;
+}
+
+int
+parse_branch_ratio(const char *input, float *branch_ratio)
+{
+	const char *str = input;
+	char *end = NULL;
+
+	while (isblank(*str))
+		str++;
+
+	if (*str == '\0')
+		return -1;
+
+	/* Go straight to the ':' separator if present */
+	while ((*str != '\0') && (*str != ':'))
+		str++;
+
+	/* Branch ratio not specified in args so leave it at default setting */
+	if (*str == '\0')
+		return 0;
+
+	/* Confirm ':' separator present */
+	if (*str != ':')
+		return -1;
+
+	str++;
+	errno = 0;
+	*branch_ratio = strtof(str, &end);
+	if (errno || end == NULL)
+		return -1;
+
+	if (*end != '\0')
+		return -1;
+
+	str = end + 1;
 
 	return str - input;
 }

examples/vm_power_manager/parse.h

@@ -12,6 +12,9 @@ extern "C" {
 int
 parse_set(const char *, uint16_t [], unsigned int);
 
+int
+parse_branch_ratio(const char *input, float *branch_ratio);
+
 #ifdef __cplusplus
 }
 #endif

examples/vm_power_manager/power_manager.c

@@ -59,7 +59,6 @@ core_info_init(void)
 	ci = get_core_info();
 
 	ci->core_count = get_nprocs_conf();
-	ci->branch_ratio_threshold = BRANCH_RATIO_THRESHOLD;
 	ci->cd = malloc(ci->core_count * sizeof(struct core_details));
 	memset(ci->cd, 0, ci->core_count * sizeof(struct core_details));
 	if (!ci->cd) {
@@ -68,6 +67,7 @@ core_info_init(void)
 	}
 	for (i = 0; i < ci->core_count; i++) {
 		ci->cd[i].global_enabled_cpus = 1;
+		ci->cd[i].branch_ratio_threshold = BRANCH_RATIO_THRESHOLD;
 	}
 	printf("%d cores in system\n", ci->core_count);
 	return 0;

examples/vm_power_manager/power_manager.h

@@ -26,12 +26,12 @@ struct core_details {
 	uint16_t freq_directions[FREQ_WINDOW_SIZE];
 	uint16_t freq_window_idx;
 	uint16_t freq_state;
+	float branch_ratio_threshold;
 };
 
 struct core_info {
 	uint16_t core_count;
 	struct core_details *cd;
-	float branch_ratio_threshold;
 };
 
 #define BRANCH_RATIO_THRESHOLD 0.1