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Date:      Thu, 17 Aug 2017 16:54:37 +0000 (UTC)
From:      Conrad Meyer <cem@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r322621 - head/sys/x86/x86
Message-ID:  <201708171654.v7HGsb7U030590@repo.freebsd.org>
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Author: cem
Date: Thu Aug 17 16:54:37 2017
New Revision: 322621
URL: https://svnweb.freebsd.org/changeset/base/322621

Log:
  Discover CPU topology on multi-die AMD Zen systems
  
  The Nodes per Processor topology information determines how many bits of the
  APIC ID represent the Node (Zeppelin die, on Zen systems) ID.  Documented in
  Ryzen and Epyc Processor Programming Reference (PPR).
  
  Correct topology information enables the scheduler to make better decisions
  on this hardware.
  
  Reviewed by:	kib@
  Tested by:	jeff@ (earlier version)
  Sponsored by:	Dell EMC Isilon
  Differential Revision:	https://reviews.freebsd.org/D11801

Modified:
  head/sys/x86/x86/mp_x86.c

Modified: head/sys/x86/x86/mp_x86.c
==============================================================================
--- head/sys/x86/x86/mp_x86.c	Thu Aug 17 14:40:48 2017	(r322620)
+++ head/sys/x86/x86/mp_x86.c	Thu Aug 17 16:54:37 2017	(r322621)
@@ -155,6 +155,7 @@ SYSCTL_INT(_machdep, OID_AUTO, hyperthreading_allowed,
 static struct topo_node topo_root;
 
 static int pkg_id_shift;
+static int node_id_shift;
 static int core_id_shift;
 static int disabled_cpus;
 
@@ -274,6 +275,15 @@ topo_probe_amd(void)
 		cpuid_count(0x8000001e, 0, p);
 		share_count = ((p[1] >> 8) & 0xff) + 1;
 		core_id_shift = mask_width(share_count);
+
+		/*
+		 * For Zen (17h), gather Nodes per Processor.  Each node is a
+		 * Zeppelin die; TR and EPYC CPUs will have multiple dies per
+		 * package.  Communication latency between dies is higher than
+		 * within them.
+		 */
+		nodes_per_socket = ((p[2] >> 8) & 0x7) + 1;
+		node_id_shift = pkg_id_shift - mask_width(nodes_per_socket);
 	}
 
 	if ((amd_feature2 & AMDID2_TOPOLOGY) != 0) {
@@ -483,7 +493,7 @@ topo_probe(void)
 		int type;
 		int subtype;
 		int id_shift;
-	} topo_layers[MAX_CACHE_LEVELS + 3];
+	} topo_layers[MAX_CACHE_LEVELS + 4];
 	struct topo_node *parent;
 	struct topo_node *node;
 	int layer;
@@ -515,6 +525,15 @@ topo_probe(void)
 		printf("Package ID shift: %u\n", topo_layers[nlayers].id_shift);
 	nlayers++;
 
+	if (pkg_id_shift > node_id_shift && node_id_shift != 0) {
+		topo_layers[nlayers].type = TOPO_TYPE_GROUP;
+		topo_layers[nlayers].id_shift = node_id_shift;
+		if (bootverbose)
+			printf("Node ID shift: %u\n",
+			    topo_layers[nlayers].id_shift);
+		nlayers++;
+	}
+
 	/*
 	 * Consider all caches to be within a package/chip
 	 * and "in front" of all sub-components like
@@ -522,6 +541,9 @@ topo_probe(void)
 	 */
 	for (i = MAX_CACHE_LEVELS - 1; i >= 0; --i) {
 		if (caches[i].present) {
+			if (node_id_shift != 0)
+				KASSERT(caches[i].id_shift <= node_id_shift,
+					("bug in APIC topology discovery"));
 			KASSERT(caches[i].id_shift <= pkg_id_shift,
 				("bug in APIC topology discovery"));
 			KASSERT(caches[i].id_shift >= core_id_shift,
@@ -720,7 +742,8 @@ x86topo_add_sched_group(struct topo_node *root, struct
 	int ncores;
 	int i;
 
-	KASSERT(root->type == TOPO_TYPE_SYSTEM || root->type == TOPO_TYPE_CACHE,
+	KASSERT(root->type == TOPO_TYPE_SYSTEM || root->type == TOPO_TYPE_CACHE ||
+	    root->type == TOPO_TYPE_GROUP,
 	    ("x86topo_add_sched_group: bad type: %u", root->type));
 	CPU_COPY(&root->cpuset, &cg_root->cg_mask);
 	cg_root->cg_count = root->cpu_count;
@@ -760,7 +783,8 @@ x86topo_add_sched_group(struct topo_node *root, struct
 	nchildren = 0;
 	node = root;
 	while (node != NULL) {
-		if (node->type != TOPO_TYPE_CACHE ||
+		if ((node->type != TOPO_TYPE_GROUP &&
+		    node->type != TOPO_TYPE_CACHE) ||
 		    (root->type != TOPO_TYPE_SYSTEM &&
 		    CPU_CMP(&node->cpuset, &root->cpuset) == 0)) {
 			node = topo_next_node(root, node);
@@ -780,7 +804,8 @@ x86topo_add_sched_group(struct topo_node *root, struct
 	node = root;
 	i = 0;
 	while (node != NULL) {
-		if (node->type != TOPO_TYPE_CACHE ||
+		if ((node->type != TOPO_TYPE_GROUP &&
+		    node->type != TOPO_TYPE_CACHE) ||
 		    (root->type != TOPO_TYPE_SYSTEM &&
 		    CPU_CMP(&node->cpuset, &root->cpuset) == 0)) {
 			node = topo_next_node(root, node);

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