This adds the ability to write the node distance for NUMA systems. This is
generally handled by the SLIT but unfortunately the large majority of systems
do not have a SLIT as Windows does not use them. Until now if no SLIT was
found all remote nodes had a distance of 20 which is ok for 2P systems but
wrong for 4P and larger.
Signed-off-by: Joachim Deguara <[email protected]>
--
Index: kernel/drivers/base/node.c
===================================================================
--- kernel.orig/drivers/base/node.c
+++ kernel/drivers/base/node.c
@@ -129,7 +129,30 @@ static ssize_t node_read_distance(struct
len += sprintf(buf + len, "\n");
return len;
}
-static SYSDEV_ATTR(distance, S_IRUGO, node_read_distance, NULL);
+
+//takes a space seperated string as the distances of online nodes
+static ssize_t node_write_distance(struct sys_device * dev, const char * buf,
+ size_t size){
+ int i, ret;
+ u8 dist;
+
+ for_each_online_node(i){
+ if (i){
+ buf = strchr(buf, ' ');
+ buf++;
+ }
+ ret = sscanf(buf, "%hu", &dist);
+ if (!ret)
+ return -EINVAL;
+ if (dist < 10)
+ dist = 10;
+ set_node_distance(dev->id, i, dist);
+ }
+ return size;
+}
+
+static SYSDEV_ATTR(distance, S_IRUGO | S_IWUSR, node_read_distance,
+ node_write_distance);
/*
Index: kernel/arch/x86_64/mm/srat.c
===================================================================
--- kernel.orig/arch/x86_64/mm/srat.c
+++ kernel/arch/x86_64/mm/srat.c
@@ -471,6 +471,18 @@ int __node_distance(int a, int b)
EXPORT_SYMBOL(__node_distance);
+void __set_node_distance(int a, int b, u8 dist)
+{
+ int index;
+
+ if (!acpi_slit)
+ return;
+ index = acpi_slit->locality_count * node_to_pxm(a);
+ acpi_slit->entry[index + node_to_pxm(b)] = dist;
+}
+
+EXPORT_SYMBOL(__set_node_distance);
+
int memory_add_physaddr_to_nid(u64 start)
{
int i, ret = 0;
Index: kernel/include/asm-x86_64/topology.h
===================================================================
--- kernel.orig/include/asm-x86_64/topology.h
+++ kernel/include/asm-x86_64/topology.h
@@ -14,7 +14,9 @@ extern cpumask_t node_to_cpumask[];
#ifdef CONFIG_ACPI_NUMA
extern int __node_distance(int, int);
+extern void __set_node_distance(int, int, u8);
#define node_distance(a,b) __node_distance(a,b)
+#define set_node_distance(a,b,dist) __set_node_distance(a,b,dist)
/* #else fallback version */
#endif
-
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