x86/PCI: initialize PCI bus node numbers early

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From: Linux Kernel Mailing List
Date: Wednesday, September 16, 2009 - 7:59 am

Gitweb:     http://git.kernel.org/linus/2547089ca2db132e307ef68848ba029a8ec2f341
Commit:     2547089ca2db132e307ef68848ba029a8ec2f341
Parent:     eaa959df299157e2640fcb3321537501b6afd9e6
Author:     Jesse Barnes <jbarnes@virtuousgeek.org>
AuthorDate: Fri Jul 10 14:04:30 2009 -0700
Committer:  Jesse Barnes <jbarnes@virtuousgeek.org>
CommitDate: Wed Sep 9 13:29:21 2009 -0700

    x86/PCI: initialize PCI bus node numbers early
    
    The current mp_bus_to_node array is initialized only by AMD specific
    code, since AMD platforms have registers that can be used for
    determining mode numbers.  On new Intel platforms it's necessary to
    initialize this array as well though, otherwise all PCI node numbers
    will be 0, when in fact they should be -1 (indicating that I/O isn't
    tied to any particular node).
    
    So move the mp_bus_to_node code into the common PCI code, and
    initialize it early with a default value of -1.  This may be overridden
    later by arch code (e.g. the AMD code).
    
    With this change, PCI consistent memory and other node specific
    allocations (e.g. skbuff allocs) should occur on the "current" node.
    If, for performance reasons, applications want to be bound to specific
    nodes, they should open their devices only after being pinned to the
    CPU where they'll run, for maximum locality.
    
    Acked-by: Yinghai Lu <yinghai@kernel.org>
    Tested-by: Jesse Brandeburg <jesse.brandeburg@gmail.com>
    Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
---
 arch/x86/pci/amd_bus.c |   64 +-------------------------------------------
 arch/x86/pci/common.c  |   69 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+), 63 deletions(-)

diff --git a/arch/x86/pci/amd_bus.c b/arch/x86/pci/amd_bus.c
index 3ffa10d..572ee97 100644
--- a/arch/x86/pci/amd_bus.c
+++ b/arch/x86/pci/amd_bus.c
@@ -15,63 +15,6 @@
  * also get peer root bus resource for io,mmio
  */
 
-#ifdef CONFIG_NUMA
-
-#define BUS_NR 256
-
-#ifdef CONFIG_X86_64
-
-static int mp_bus_to_node[BUS_NR];
-
-void set_mp_bus_to_node(int busnum, int node)
-{
-	if (busnum >= 0 &&  busnum < BUS_NR)
-		mp_bus_to_node[busnum] = node;
-}
-
-int get_mp_bus_to_node(int busnum)
-{
-	int node = -1;
-
-	if (busnum < 0 || busnum > (BUS_NR - 1))
-		return node;
-
-	node = mp_bus_to_node[busnum];
-
-	/*
-	 * let numa_node_id to decide it later in dma_alloc_pages
-	 * if there is no ram on that node
-	 */
-	if (node != -1 && !node_online(node))
-		node = -1;
-
-	return node;
-}
-
-#else /* CONFIG_X86_32 */
-
-static unsigned char mp_bus_to_node[BUS_NR];
-
-void set_mp_bus_to_node(int busnum, int node)
-{
-	if (busnum >= 0 &&  busnum < BUS_NR)
-	mp_bus_to_node[busnum] = (unsigned char) node;
-}
-
-int get_mp_bus_to_node(int busnum)
-{
-	int node;
-
-	if (busnum < 0 || busnum > (BUS_NR - 1))
-		return 0;
-	node = mp_bus_to_node[busnum];
-	return node;
-}
-
-#endif /* CONFIG_X86_32 */
-
-#endif /* CONFIG_NUMA */
-
 #ifdef CONFIG_X86_64
 
 /*
@@ -301,11 +244,6 @@ static int __init early_fill_mp_bus_info(void)
 	u64 val;
 	u32 address;
 
-#ifdef CONFIG_NUMA
-	for (i = 0; i < BUS_NR; i++)
-		mp_bus_to_node[i] = -1;
-#endif
-
 	if (!early_pci_allowed())
 		return -1;
 
@@ -346,7 +284,7 @@ static int __init early_fill_mp_bus_info(void)
 		node = (reg >> 4) & 0x07;
 #ifdef CONFIG_NUMA
 		for (j = min_bus; j <= max_bus; j++)
-			mp_bus_to_node[j] = (unsigned char) node;
+			set_mp_bus_to_node(j, node);
 #endif
 		link = (reg >> 8) & 0x03;
 
diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
index 2202b62..5db96d4 100644
--- a/arch/x86/pci/common.c
+++ b/arch/x86/pci/common.c
@@ -600,3 +600,72 @@ struct pci_bus * __devinit pci_scan_bus_with_sysdata(int busno)
 {
 	return pci_scan_bus_on_node(busno, &pci_root_ops, -1);
 }
+
+/*
+ * NUMA info for PCI busses
+ *
+ * Early arch code is responsible for filling in reasonable values here.
+ * A node id of "-1" means "use current node".  In other words, if a bus
+ * has a -1 node id, it's not tightly coupled to any particular chunk
+ * of memory (as is the case on some Nehalem systems).
+ */
+#ifdef CONFIG_NUMA
+
+#define BUS_NR 256
+
+#ifdef CONFIG_X86_64
+
+static int mp_bus_to_node[BUS_NR] = {
+	[0 ... BUS_NR - 1] = -1
+};
+
+void set_mp_bus_to_node(int busnum, int node)
+{
+	if (busnum >= 0 &&  busnum < BUS_NR)
+		mp_bus_to_node[busnum] = node;
+}
+
+int get_mp_bus_to_node(int busnum)
+{
+	int node = -1;
+
+	if (busnum < 0 || busnum > (BUS_NR - 1))
+		return node;
+
+	node = mp_bus_to_node[busnum];
+
+	/*
+	 * let numa_node_id to decide it later in dma_alloc_pages
+	 * if there is no ram on that node
+	 */
+	if (node != -1 && !node_online(node))
+		node = -1;
+
+	return node;
+}
+
+#else /* CONFIG_X86_32 */
+
+static unsigned char mp_bus_to_node[BUS_NR] = {
+	[0 ... BUS_NR - 1] = -1
+};
+
+void set_mp_bus_to_node(int busnum, int node)
+{
+	if (busnum >= 0 &&  busnum < BUS_NR)
+	mp_bus_to_node[busnum] = (unsigned char) node;
+}
+
+int get_mp_bus_to_node(int busnum)
+{
+	int node;
+
+	if (busnum < 0 || busnum > (BUS_NR - 1))
+		return 0;
+	node = mp_bus_to_node[busnum];
+	return node;
+}
+
+#endif /* CONFIG_X86_32 */
+
+#endif /* CONFIG_NUMA */
--
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x86/PCI: initialize PCI bus node numbers early, Linux Kernel Mailing ..., (Wed Sep 16, 7:59 am)