From 0241b85bc17d0522eaddedad24cc9c57fcdc4b39 Mon Sep 17 00:00:00 2001
From: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Date: Wed, 20 Dec 2017 09:19:43 +0900
Subject: [PATCH] iscsi: Remove DPDK dependency and simplify load balancing

Load balancing for idle iSCSI connections uses the RTE EAL Launch
state and uses DPDK RTE EAL API.

But all SPDK reactors will exit simultaneously because each SPDK
reactor checks if the global state is RUNNING to exit.

Hence calling rte_eal_get_lcore_state() is not necessary.

When the reactor hot-plug function is supported, this implementation
will be reconsidered together.

Change-Id: I34eaf3e42b5b7deae6473d2bfaf0910aaa9da6de
Signed-off-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-on: https://review.gerrithub.io/391339
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
---
 lib/iscsi/conn.c | 56 +++++++++++++-----------------------------------
 1 file changed, 15 insertions(+), 41 deletions(-)

diff --git a/lib/iscsi/conn.c b/lib/iscsi/conn.c
index 75baeef3c..a4d097d78 100644
--- a/lib/iscsi/conn.c
+++ b/lib/iscsi/conn.c
@@ -35,7 +35,6 @@
 #include "spdk/stdinc.h"
 
 #include <rte_config.h>
-#include <rte_mempool.h>
 
 #if defined(__FreeBSD__)
 #include <sys/event.h>
@@ -1591,56 +1590,31 @@ static uint32_t
 spdk_iscsi_conn_allocate_reactor(uint64_t cpumask)
 {
 	uint32_t i, selected_core;
-	enum rte_lcore_state_t state;
-	uint32_t first_core = spdk_env_get_first_core();
 	int32_t num_pollers, min_pollers;
 
-	cpumask &= spdk_app_get_core_mask();
-	if (cpumask == 0) {
-		return first_core;
-	}
-
 	min_pollers = INT_MAX;
-	selected_core = 0;
+	selected_core = spdk_env_get_first_core();
 
 	/* we use u64 as CPU core mask */
-	for (i = 0; i < RTE_MAX_LCORE && i < 64; i++) {
+	SPDK_ENV_FOREACH_CORE(i) {
 		if (!((1ULL << i) & cpumask)) {
 			continue;
 		}
 
-		/*
-		 * DPDK returns WAIT for the master core instead of RUNNING.
-		 * So we always treat the reactor on master core as RUNNING.
-		 */
-		if (i == first_core) {
-			state = RUNNING;
-		} else {
-			state = rte_eal_get_lcore_state(i);
-		}
+		/* This core is running. Check how many pollers it already has. */
+		num_pollers = g_num_connections[i];
 
-		switch (state) {
-		case WAIT:
-		case FINISHED:
-			/* reactor does not run on the lcore */
-			break;
-		case RUNNING:
-			/* This lcore is running. Check how many pollers it already has. */
-			num_pollers = g_num_connections[i];
-
-			if ((num_pollers > 0) && (num_pollers < g_connections_per_lcore)) {
-				/* Fewer than the maximum connections per lcore,
-				 * but at least 1. Use this lcore.
-				 */
-				return i;
-			} else if (num_pollers < min_pollers) {
-				/* Track the core that has the minimum number of pollers
-				 * to be used if no cores meet our criteria
-				 */
-				selected_core = i;
-				min_pollers = num_pollers;
-			}
-			break;
+		if ((num_pollers > 0) && (num_pollers < g_connections_per_lcore)) {
+			/* Fewer than the maximum connections per core,
+			 * but at least 1. Use this core.
+			 */
+			return i;
+		} else if (num_pollers < min_pollers) {
+			/* Track the core that has the minimum number of pollers
+			 * to be used if no cores meet our criteria
+			 */
+			selected_core = i;
+			min_pollers = num_pollers;
 		}
 	}