[PATCH v12 3/3] examples/l3fwd-power: add PM QoS configuration

[Huisong Li]

The '--cpu-resume-latency' can use to control C-state selection.
Setting the CPU resume latency to 0 can limit the CPU just to enter
C0-state to improve performance, which also may increase the power
consumption of platform.

Signed-off-by: Huisong Li <lihuisong at huawei.com>
Acked-by: Morten Brørup <mb at smartsharesystems.com>
Acked-by: Chengwen Feng <fengchengwen at huawei.com>
---
 .../sample_app_ug/l3_forward_power_man.rst    |  5 +-
 examples/l3fwd-power/main.c                   | 68 +++++++++++++++++++
 2 files changed, 72 insertions(+), 1 deletion(-)

diff --git a/doc/guides/sample_app_ug/l3_forward_power_man.rst b/doc/guides/sample_app_ug/l3_forward_power_man.rst
index 9c9684fea7..70fa83669a 100644
--- a/doc/guides/sample_app_ug/l3_forward_power_man.rst
+++ b/doc/guides/sample_app_ug/l3_forward_power_man.rst
@@ -67,7 +67,8 @@ based on the speculative sleep duration of the core.
 In this application, we introduce a heuristic algorithm that allows packet processing cores to sleep for a short period
 if there is no Rx packet received on recent polls.
 In this way, CPUIdle automatically forces the corresponding cores to enter deeper C-states
-instead of always running to the C0 state waiting for packets.
+instead of always running to the C0 state waiting for packets. But user can set the CPU resume latency to control C-state selection.
+Setting the CPU resume latency to 0 can limit the CPU just to enter C0-state to improve performance, which may increase power consumption of platform.
 
 .. note::
 
@@ -105,6 +106,8 @@ where,
 
 *   --config (port,queue,lcore)[,(port,queue,lcore)]: determines which queues from which ports are mapped to which cores.
 
+*   --cpu-resume-latency LATENCY: set CPU resume latency to control C-state selection, 0 : just allow to enter C0-state.
+
 *   --max-pkt-len: optional, maximum packet length in decimal (64-9600)
 
 *   --no-numa: optional, disables numa awareness
diff --git a/examples/l3fwd-power/main.c b/examples/l3fwd-power/main.c
index 0ce4aa04d4..e58f4e301c 100644
--- a/examples/l3fwd-power/main.c
+++ b/examples/l3fwd-power/main.c
@@ -47,6 +47,7 @@
 #include <rte_telemetry.h>
 #include <rte_power_pmd_mgmt.h>
 #include <rte_power_uncore.h>
+#include <rte_power_qos.h>
 
 #include "perf_core.h"
 #include "main.h"
@@ -265,6 +266,9 @@ static uint32_t pause_duration = 1;
 static uint32_t scale_freq_min;
 static uint32_t scale_freq_max;
 
+static int cpu_resume_latency;
+static bool pm_qos_en;
+
 static struct rte_mempool * pktmbuf_pool[NB_SOCKETS];
 
 
@@ -1501,6 +1505,8 @@ print_usage(const char *prgname)
 		"  -U: set min/max frequency for uncore to maximum value\n"
 		"  -i (frequency index): set min/max frequency for uncore to specified frequency index\n"
 		"  --config (port,queue,lcore): rx queues configuration\n"
+		"  --cpu-resume-latency LATENCY: set CPU resume latency to control C-state selection,"
+		" 0 : just allow to enter C0-state\n"
 		"  --high-perf-cores CORELIST: list of high performance cores\n"
 		"  --perf-config: similar as config, cores specified as indices"
 		" for bins containing high or regular performance cores\n"
@@ -1545,6 +1551,28 @@ parse_uint32(const char *opt, uint32_t *res)
 	return 0;
 }
 
+static int
+parse_int(const char *opt, int *res)
+{
+	char *end = NULL;
+	signed long val;
+
+	/* parse integer string */
+	val = strtol(opt, &end, 10);
+	if ((opt[0] == '\0') || (end == NULL) || (*end != '\0'))
+		return -1;
+
+	if (val < INT_MIN || val > INT_MAX) {
+		RTE_LOG(ERR, L3FWD_POWER, "parameter should be range from %d to %d.\n",
+			INT_MIN, INT_MAX);
+		return -1;
+	}
+
+	*res = val;
+
+	return 0;
+}
+
 static int
 parse_uncore_options(enum uncore_choice choice, const char *argument)
 {
@@ -1734,6 +1762,7 @@ parse_pmd_mgmt_config(const char *name)
 #define CMD_LINE_OPT_PAUSE_DURATION "pause-duration"
 #define CMD_LINE_OPT_SCALE_FREQ_MIN "scale-freq-min"
 #define CMD_LINE_OPT_SCALE_FREQ_MAX "scale-freq-max"
+#define CMD_LINE_OPT_CPU_RESUME_LATENCY "cpu-resume-latency"
 
 /* Parse the argument given in the command line of the application */
 static int
@@ -1748,6 +1777,7 @@ parse_args(int argc, char **argv)
 		{"perf-config", 1, 0, 0},
 		{"high-perf-cores", 1, 0, 0},
 		{"no-numa", 0, 0, 0},
+		{CMD_LINE_OPT_CPU_RESUME_LATENCY, 1, 0, 0},
 		{CMD_LINE_OPT_MAX_PKT_LEN, 1, 0, 0},
 		{CMD_LINE_OPT_PARSE_PTYPE, 0, 0, 0},
 		{CMD_LINE_OPT_LEGACY, 0, 0, 0},
@@ -1933,6 +1963,15 @@ parse_args(int argc, char **argv)
 				printf("Scaling frequency maximum configured\n");
 			}
 
+			if (!strncmp(lgopts[option_index].name,
+					CMD_LINE_OPT_CPU_RESUME_LATENCY,
+					sizeof(CMD_LINE_OPT_CPU_RESUME_LATENCY))) {
+				if (parse_int(optarg, &cpu_resume_latency) != 0)
+					return -1;
+				printf("PM QoS configured\n");
+				pm_qos_en = true;
+			}
+
 			break;
 
 		default:
@@ -2256,6 +2295,26 @@ init_power_library(void)
 			return -1;
 		}
 	}
+
+	if (pm_qos_en) {
+		RTE_LCORE_FOREACH(lcore_id) {
+			/*
+			 * Set the cpu resume latency of the worker lcore based
+			 * on user's request. If set strict latency (0), just
+			 * allow the CPU to enter the shallowest idle state to
+			 * improve performance.
+			 */
+			ret = rte_power_qos_set_cpu_resume_latency(lcore_id,
+							cpu_resume_latency);
+			if (ret != 0) {
+				RTE_LOG(ERR, L3FWD_POWER,
+					"Failed to set cpu resume latency on lcore-%u.\n",
+					lcore_id);
+				return ret;
+			}
+		}
+	}
+
 	return ret;
 }
 
@@ -2295,6 +2354,15 @@ deinit_power_library(void)
 			}
 		}
 	}
+
+	if (pm_qos_en) {
+		RTE_LCORE_FOREACH(lcore_id) {
+			/* Restore the original value in kernel. */
+			rte_power_qos_set_cpu_resume_latency(lcore_id,
+					RTE_POWER_QOS_RESUME_LATENCY_NO_CONSTRAINT);
+		}
+	}
+
 	return ret;
 }
 
-- 
2.22.0