On Wed, 27 Feb 2019 15:50:32 -0700 Keith Busch <[email protected]> wrote:
> Systems may be constructed with various specialized nodes. Some nodes > may provide memory, some provide compute devices that access and use > that memory, and others may provide both. Nodes that provide memory are > referred to as memory targets, and nodes that can initiate memory access > are referred to as memory initiators. > > Memory targets will often have varying access characteristics from > different initiators, and platforms may have ways to express those > relationships. In preparation for these systems, provide interfaces for > the kernel to export the memory relationship among different nodes memory > targets and their initiators with symlinks to each other. > > If a system provides access locality for each initiator-target pair, nodes > may be grouped into ranked access classes relative to other nodes. The > new interface allows a subsystem to register relationships of varying > classes if available and desired to be exported. > > A memory initiator may have multiple memory targets in the same access > class. The target memory's initiators in a given class indicate the > nodes access characteristics share the same performance relative to other > linked initiator nodes. Each target within an initiator's access class, > though, do not necessarily perform the same as each other. > > A memory target node may have multiple memory initiators. All linked > initiators in a target's class have the same access characteristics to > that target. > > The following example show the nodes' new sysfs hierarchy for a memory > target node 'Y' with access class 0 from initiator node 'X': > > # symlinks -v /sys/devices/system/node/nodeX/access0/ > relative: /sys/devices/system/node/nodeX/access0/targets/nodeY -> > ../../nodeY > > # symlinks -v /sys/devices/system/node/nodeY/access0/ > relative: /sys/devices/system/node/nodeY/access0/initiators/nodeX -> > ../../nodeX > > The new attributes are added to the sysfs stable documentation. > > Signed-off-by: Keith Busch <[email protected]> A couple of minor bits inline. With those tidied up. Reviewed-by: Jonathan Cameron <[email protected]> Thanks, > --- > Documentation/ABI/stable/sysfs-devices-node | 25 ++++- > drivers/base/node.c | 142 > +++++++++++++++++++++++++++- > include/linux/node.h | 7 +- > 3 files changed, 171 insertions(+), 3 deletions(-) > > diff --git a/Documentation/ABI/stable/sysfs-devices-node > b/Documentation/ABI/stable/sysfs-devices-node > index 3e90e1f3bf0a..fb843222a281 100644 > --- a/Documentation/ABI/stable/sysfs-devices-node > +++ b/Documentation/ABI/stable/sysfs-devices-node > @@ -90,4 +90,27 @@ Date: December 2009 > Contact: Lee Schermerhorn <[email protected]> > Description: > The node's huge page size control/query attributes. > - See Documentation/admin-guide/mm/hugetlbpage.rst > \ No newline at end of file > + See Documentation/admin-guide/mm/hugetlbpage.rst > + > +What: /sys/devices/system/node/nodeX/accessY/ > +Date: December 2018 > +Contact: Keith Busch <[email protected]> > +Description: > + The node's relationship to other nodes for access class "Y". > + > +What: /sys/devices/system/node/nodeX/accessY/initiators/ > +Date: December 2018 > +Contact: Keith Busch <[email protected]> > +Description: > + The directory containing symlinks to memory initiator > + 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. > + > +What: /sys/devices/system/node/nodeX/classY/targets/ accessY > +Date: December 2018 > +Contact: Keith Busch <[email protected]> > +Description: > + The directory containing symlinks to memory targets that > + this initiator node has class "Y" access. > diff --git a/drivers/base/node.c b/drivers/base/node.c > index 86d6cd92ce3d..6f4097680580 100644 > --- a/drivers/base/node.c > +++ b/drivers/base/node.c > @@ -17,6 +17,7 @@ > #include <linux/nodemask.h> > #include <linux/cpu.h> > #include <linux/device.h> > +#include <linux/pm_runtime.h> > #include <linux/swap.h> > #include <linux/slab.h> > > @@ -59,6 +60,94 @@ static inline ssize_t node_read_cpulist(struct device *dev, > static DEVICE_ATTR(cpumap, S_IRUGO, node_read_cpumask, NULL); > static DEVICE_ATTR(cpulist, S_IRUGO, node_read_cpulist, NULL); > > +/** > + * struct node_access_nodes - Access class device to hold user visible > + * relationships to other nodes. > + * @dev: Device for this memory access class > + * @list_node: List element in the node's access list > + * @access: The access class rank > + */ > +struct node_access_nodes { > + struct device dev; > + struct list_head list_node; > + unsigned access; > +}; > +#define to_access_nodes(dev) container_of(dev, struct node_access_nodes, dev) > + > +static struct attribute *node_init_access_node_attrs[] = { > + NULL, > +}; > + > +static struct attribute *node_targ_access_node_attrs[] = { > + NULL, > +}; > + > +static const struct attribute_group initiators = { > + .name = "initiators", > + .attrs = node_init_access_node_attrs, > +}; > + > +static const struct attribute_group targets = { > + .name = "targets", > + .attrs = node_targ_access_node_attrs, > +}; > + > +static const struct attribute_group *node_access_node_groups[] = { > + &initiators, > + &targets, > + NULL, > +}; > + > +static void node_remove_accesses(struct node *node) > +{ > + struct node_access_nodes *c, *cnext; > + > + list_for_each_entry_safe(c, cnext, &node->access_list, list_node) { > + list_del(&c->list_node); > + device_unregister(&c->dev); > + } > +} > + > +static void node_access_release(struct device *dev) > +{ > + kfree(to_access_nodes(dev)); > +} > + > +static struct node_access_nodes *node_init_node_access(struct node *node, > + unsigned access) > +{ > + struct node_access_nodes *access_node; > + struct device *dev; > + > + list_for_each_entry(access_node, &node->access_list, list_node) > + if (access_node->access == access) > + return access_node; > + > + access_node = kzalloc(sizeof(*access_node), GFP_KERNEL); > + if (!access_node) > + return NULL; > + > + access_node->access = access; > + dev = &access_node->dev; > + dev->parent = &node->dev; > + dev->release = node_access_release; > + dev->groups = node_access_node_groups; > + if (dev_set_name(dev, "access%u", access)) > + goto free; > + > + if (device_register(dev)) > + goto free_name; > + > + pm_runtime_no_callbacks(dev); > + list_add_tail(&access_node->list_node, &node->access_list); > + return access_node; > +free_name: > + kfree_const(dev->kobj.name); > +free: > + kfree(access_node); > + return NULL; > +} > + > #define K(x) ((x) << (PAGE_SHIFT - 10)) > static ssize_t node_read_meminfo(struct device *dev, > struct device_attribute *attr, char *buf) > @@ -340,7 +429,7 @@ static int register_node(struct node *node, int num) > void unregister_node(struct node *node) > { > hugetlb_unregister_node(node); /* no-op, if memoryless node */ > - > + node_remove_accesses(node); > device_unregister(&node->dev); > } > > @@ -372,6 +461,56 @@ int register_cpu_under_node(unsigned int cpu, unsigned > int nid) > kobject_name(&node_devices[nid]->dev.kobj)); > } > > +/** > + * register_memory_node_under_compute_node - link memory node to its compute > + * node for a given access class. > + * @mem_node: Memory node number > + * @cpu_node: Cpu node number > + * @access: Access class to register > + * > + * Description: > + * For use with platforms that may have separate memory and compute nodes. > + * This function will export node relationships linking which memory > + * initiator nodes can access memory targets at a given ranked access > + * class. > + */ > +int register_memory_node_under_compute_node(unsigned int mem_nid, > + unsigned int cpu_nid, > + unsigned access) > +{ > + struct node *init_node, *targ_node; > + struct node_access_nodes *initiator, *target; > + int ret; > + > + if (!node_online(cpu_nid) || !node_online(mem_nid)) > + return -ENODEV; > + > + init_node = node_devices[cpu_nid]; > + targ_node = node_devices[mem_nid]; > + initiator = node_init_node_access(init_node, access); > + target = node_init_node_access(targ_node, access); > + if (!initiator || !target) > + return -ENOMEM; > + > + ret = sysfs_add_link_to_group(&initiator->dev.kobj, "targets", > + &targ_node->dev.kobj, > + dev_name(&targ_node->dev)); > + if (ret) > + return ret; > + > + ret = sysfs_add_link_to_group(&target->dev.kobj, "initiators", > + &init_node->dev.kobj, > + dev_name(&init_node->dev)); > + if (ret) > + goto err; > + > + return 0; > + err: > + sysfs_remove_link_from_group(&initiator->dev.kobj, "targets", > + dev_name(&targ_node->dev)); > + return ret; > +} > + > int unregister_cpu_under_node(unsigned int cpu, unsigned int nid) > { > struct device *obj; > @@ -580,6 +719,7 @@ int __register_one_node(int nid) > register_cpu_under_node(cpu, nid); > } > > + INIT_LIST_HEAD(&node_devices[nid]->access_list); > /* initialize work queue for memory hot plug */ > init_node_hugetlb_work(nid); > > diff --git a/include/linux/node.h b/include/linux/node.h > index 257bb3d6d014..f34688a203c1 100644 > --- a/include/linux/node.h > +++ b/include/linux/node.h > @@ -17,11 +17,12 @@ > > #include <linux/device.h> > #include <linux/cpumask.h> > +#include <linux/list.h> > #include <linux/workqueue.h> > > struct node { > struct device dev; > - > + struct list_head access_list; Nitpick if you are rerolling for some reason. The separation before the ifdef was nice from a readability point of view. > #if defined(CONFIG_MEMORY_HOTPLUG_SPARSE) && defined(CONFIG_HUGETLBFS) > struct work_struct node_work; > #endif > @@ -75,6 +76,10 @@ extern int register_mem_sect_under_node(struct > memory_block *mem_blk, > extern int unregister_mem_sect_under_nodes(struct memory_block *mem_blk, > unsigned long phys_index); > > +extern int register_memory_node_under_compute_node(unsigned int mem_nid, > + unsigned int cpu_nid, > + unsigned access); > + > #ifdef CONFIG_HUGETLBFS > extern void register_hugetlbfs_with_node(node_registration_func_t doregister, > node_registration_func_t unregister);
