MEDIUM: cfgparse: numa detect topology on FreeBSD.

allowing for all platforms supporting cpu affinity to have a chance
 to detect the cpu topology from a given valid node (e.g.
 DragonflyBSD seems to be NUMA aware from a kernel's perspective
 and seems to be willing start to provide userland means to get
 proper info).

include/haproxy/cpuset-t.h

@@ -9,6 +9,7 @@
 #ifdef __FreeBSD__
 #include <sys/_cpuset.h>
 #include <sys/cpuset.h>
+#include <sys/sysctl.h>
 #include <strings.h>
 #endif
 #endif

src/cfgparse.c

@@ -2375,6 +2375,50 @@ static int numa_detect_topology()
 	return ha_cpuset_count(&node_cpu_set);
 }
 
+#elif defined(__FreeBSD__)
+static int numa_detect_topology()
+{
+	struct hap_cpuset node_cpu_set;
+	int ndomains = 0, i;
+	size_t len = sizeof(ndomains);
+
+	if (sysctlbyname("vm.ndomains", &ndomains, &len, NULL, 0) == -1) {
+		ha_notice("Cannot assess the number of CPUs domains\n");
+		return 0;
+	}
+
+	BUG_ON(ndomains > MAXMEMDOM);
+	ha_cpuset_zero(&node_cpu_set);
+
+	/*
+	 * We retrieve the first active valid CPU domain
+	 * with active cpu and binding it, we returns
+	 * the number of cpu from the said domain
+	 */
+	for (i = 0; i < ndomains; i ++) {
+		struct hap_cpuset dom;
+		ha_cpuset_zero(&dom);
+		if (cpuset_getaffinity(CPU_LEVEL_WHICH, CPU_WHICH_DOMAIN, i, sizeof(dom.cpuset), &dom.cpuset) == -1)
+			continue;
+
+		if (!ha_cpuset_count(&dom))
+			continue;
+
+		ha_cpuset_assign(&node_cpu_set, &dom);
+
+		ha_diag_warning("Multi-socket cpu detected, automatically binding on active CPUs of '%d' (%u active cpu(s))\n", i, ha_cpuset_count(&node_cpu_set));
+		if (cpuset_setaffinity(CPU_LEVEL_WHICH, CPU_WHICH_PID, -1, sizeof(node_cpu_set.cpuset), &node_cpu_set.cpuset) == -1) {
+			ha_warning("Cannot set the cpu affinity for this multi-cpu machine\n");
+
+			/* clear the cpuset used as return value */
+			ha_cpuset_zero(&node_cpu_set);
+		}
+		break;
+	}
+
+	return ha_cpuset_count(&node_cpu_set);
+}
+
 #else
 static int numa_detect_topology()
 {