@@ -106,7 +106,8 @@ Description:
nodes that have class "Y" access to this target node's
memory. CPUs and other memory initiators in nodes not in
the list accessing this node's memory may have different
- performance.
+ performance. This directory also provides the performance
+ attributes if they exist.
What: /sys/devices/system/node/nodeX/classY/targets/
Date: December 2018
@@ -114,3 +115,31 @@ Contact: Keith Busch <keith.busch@intel.com>
Description:
The directory containing symlinks to memory targets that
this initiator node has class "Y" access.
+
+What: /sys/devices/system/node/nodeX/accessY/initiators/read_bandwidth
+Date: December 2018
+Contact: Keith Busch <keith.busch@intel.com>
+Description:
+ This node's read bandwidth in MB/s when accessed from
+ nodes found in this access class's linked initiators.
+
+What: /sys/devices/system/node/nodeX/accessY/initiators/read_latency
+Date: December 2018
+Contact: Keith Busch <keith.busch@intel.com>
+Description:
+ This node's read latency in nanoseconds when accessed
+ from nodes found in this access class's linked initiators.
+
+What: /sys/devices/system/node/nodeX/accessY/initiators/write_bandwidth
+Date: December 2018
+Contact: Keith Busch <keith.busch@intel.com>
+Description:
+ This node's write bandwidth in MB/s when accessed from
+ found in this access class's linked initiators.
+
+What: /sys/devices/system/node/nodeX/accessY/initiators/write_latency
+Date: December 2018
+Contact: Keith Busch <keith.busch@intel.com>
+Description:
+ This node's write latency in nanoseconds when access
+ from nodes found in this class's linked initiators.
@@ -149,6 +149,14 @@ config DEBUG_TEST_DRIVER_REMOVE
unusable. You should say N here unless you are explicitly looking to
test this functionality.
+config HMEM_REPORTING
+ bool
+ default n
+ depends on NUMA
+ help
+ Enable reporting for heterogenous memory access attributes under
+ their non-uniform memory nodes.
+
source "drivers/base/test/Kconfig"
config SYS_HYPERVISOR
@@ -71,6 +71,9 @@ struct node_access_nodes {
struct device dev;
struct list_head list_node;
unsigned access;
+#ifdef CONFIG_HMEM_REPORTING
+ struct node_hmem_attrs hmem_attrs;
+#endif
};
#define to_access_nodes(dev) container_of(dev, struct node_access_nodes, dev)
@@ -148,6 +151,62 @@ static struct node_access_nodes *node_init_node_access(struct node *node,
return NULL;
}
+#ifdef CONFIG_HMEM_REPORTING
+#define ACCESS_ATTR(name) \
+static ssize_t name##_show(struct device *dev, \
+ struct device_attribute *attr, \
+ char *buf) \
+{ \
+ return sprintf(buf, "%u\n", to_access_nodes(dev)->hmem_attrs.name); \
+} \
+static DEVICE_ATTR_RO(name);
+
+ACCESS_ATTR(read_bandwidth)
+ACCESS_ATTR(read_latency)
+ACCESS_ATTR(write_bandwidth)
+ACCESS_ATTR(write_latency)
+
+static struct attribute *access_attrs[] = {
+ &dev_attr_read_bandwidth.attr,
+ &dev_attr_read_latency.attr,
+ &dev_attr_write_bandwidth.attr,
+ &dev_attr_write_latency.attr,
+ NULL,
+};
+
+/**
+ * node_set_perf_attrs - Set the performance values for given access class
+ * @nid: Node identifier to be set
+ * @hmem_attrs: Heterogeneous memory performance attributes
+ * @access: The access class the for the given attributes
+ */
+void node_set_perf_attrs(unsigned int nid, struct node_hmem_attrs *hmem_attrs,
+ unsigned access)
+{
+ struct node_access_nodes *c;
+ struct node *node;
+ int i;
+
+ if (WARN_ON_ONCE(!node_online(nid)))
+ return;
+
+ node = node_devices[nid];
+ c = node_init_node_access(node, access);
+ if (!c)
+ return;
+
+ c->hmem_attrs = *hmem_attrs;
+ for (i = 0; access_attrs[i] != NULL; i++) {
+ if (sysfs_add_file_to_group(&c->dev.kobj, access_attrs[i],
+ "initiators")) {
+ pr_info("failed to add performance attribute to node %d\n",
+ nid);
+ break;
+ }
+ }
+}
+#endif
+
#define K(x) ((x) << (PAGE_SHIFT - 10))
static ssize_t node_read_meminfo(struct device *dev,
struct device_attribute *attr, char *buf)
@@ -20,6 +20,25 @@
#include <linux/list.h>
#include <linux/workqueue.h>
+#ifdef CONFIG_HMEM_REPORTING
+/**
+ * struct node_hmem_attrs - heterogeneous memory performance attributes
+ *
+ * @read_bandwidth: Read bandwidth in MB/s
+ * @write_bandwidth: Write bandwidth in MB/s
+ * @read_latency: Read latency in nanoseconds
+ * @write_latency: Write latency in nanoseconds
+ */
+struct node_hmem_attrs {
+ unsigned int read_bandwidth;
+ unsigned int write_bandwidth;
+ unsigned int read_latency;
+ unsigned int write_latency;
+};
+void node_set_perf_attrs(unsigned int nid, struct node_hmem_attrs *hmem_attrs,
+ unsigned access);
+#endif
+
struct node {
struct device dev;
struct list_head access_list;
Heterogeneous memory systems provide memory nodes with different latency and bandwidth performance attributes. Provide a new kernel interface for subsystems to register the attributes under the memory target node's initiator access class. If the system provides this information, applications may query these attributes when deciding which node to request memory. The following example shows the new sysfs hierarchy for a node exporting performance attributes: # tree -P "read*|write*"/sys/devices/system/node/nodeY/accessZ/initiators/ /sys/devices/system/node/nodeY/accessZ/initiators/ |-- read_bandwidth |-- read_latency |-- write_bandwidth `-- write_latency The bandwidth is exported as MB/s and latency is reported in nanoseconds. The values are taken from the platform as reported by the manufacturer. Memory accesses from an initiator node that is not one of the memory's access "Z" initiator nodes linked in the same directory may observe different performance than reported here. When a subsystem makes use of this interface, initiators of a different access number may not have the same performance relative to initiators in other access numbers, or omitted from the any access class' initiators. Descriptions for memory access initiator performance access attributes are added to sysfs stable documentation. Signed-off-by: Keith Busch <keith.busch@intel.com> --- Documentation/ABI/stable/sysfs-devices-node | 31 ++++++++++++++- drivers/base/Kconfig | 8 ++++ drivers/base/node.c | 59 +++++++++++++++++++++++++++++ include/linux/node.h | 19 ++++++++++ 4 files changed, 116 insertions(+), 1 deletion(-)