Wei Xu <weixugc@xxxxxxxxxx> writes:
> On Thu, May 12, 2022 at 12:12 AM Aneesh Kumar K V
> <aneesh.kumar@xxxxxxxxxxxxx> wrote:
>>
>> On 5/12/22 12:33 PM, ying.huang@xxxxxxxxx wrote:
>> > On Wed, 2022-05-11 at 23:22 -0700, Wei Xu wrote:
>> >> Sysfs Interfaces
>> >> ================
>> >>
>> >> * /sys/devices/system/memtier/memtierN/nodelist
>> >>
>> >> where N = 0, 1, 2 (the kernel supports only 3 tiers for now).
>> >>
>> >> Format: node_list
>> >>
>> >> Read-only. When read, list the memory nodes in the specified tier.
>> >>
>> >> Tier 0 is the highest tier, while tier 2 is the lowest tier.
>> >>
>> >> The absolute value of a tier id number has no specific meaning.
>> >> What matters is the relative order of the tier id numbers.
>> >>
>> >> When a memory tier has no nodes, the kernel can hide its memtier
>> >> sysfs files.
>> >>
>> >> * /sys/devices/system/node/nodeN/memtier
>> >>
>> >> where N = 0, 1, ...
>> >>
>> >> Format: int or empty
>> >>
>> >> When read, list the memory tier that the node belongs to. Its value
>> >> is empty for a CPU-only NUMA node.
>> >>
>> >> When written, the kernel moves the node into the specified memory
>> >> tier if the move is allowed. The tier assignment of all other nodes
>> >> are not affected.
>> >>
>> >> Initially, we can make this interface read-only.
>> >
>> > It seems that "/sys/devices/system/node/nodeN/memtier" has all
>> > information we needed. Do we really need
>> > "/sys/devices/system/memtier/memtierN/nodelist"?
>> >
>> > That can be gotten via a simple shell command line,
>> >
>> > $ grep . /sys/devices/system/node/nodeN/memtier | sort -n -k 2 -t ':'
>> >
>>
>> It will be really useful to fetch the memory tier node list in an easy
>> fashion rather than reading multiple sysfs directories. If we don't have
>> other attributes for memorytier, we could keep
>> "/sys/devices/system/memtier/memtierN" a NUMA node list there by
>> avoiding /sys/devices/system/memtier/memtierN/nodelist
>>
>> -aneesh
>
> It is harder to implement memtierN as just a file and doesn't follow
> the existing sysfs pattern, either. Besides, it is extensible to have
> memtierN as a directory.
diff --git a/drivers/base/node.c b/drivers/base/node.c
index 6248326f944d..251f38ec3816 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -1097,12 +1097,49 @@ static struct attribute *node_state_attrs[] = {
NULL
};
+#define MAX_TIER 3
+nodemask_t memory_tier[MAX_TIER];
+
+#define _TIER_ATTR_RO(name, tier_index) \
+ { __ATTR(name, 0444, show_tier, NULL), tier_index, NULL }
+
+struct memory_tier_attr {
+ struct device_attribute attr;
+ int tier_index;
+ int (*write)(nodemask_t nodes);
+};
+
+static ssize_t show_tier(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct memory_tier_attr *mt = container_of(attr, struct memory_tier_attr, attr);
+
+ return sysfs_emit(buf, "%*pbl\n",
+ nodemask_pr_args(&memory_tier[mt->tier_index]));
+}
+
static const struct attribute_group memory_root_attr_group = {
.attrs = node_state_attrs,
};
+
+#define TOP_TIER 0
+static struct memory_tier_attr memory_tiers[] = {
+ [0] = _TIER_ATTR_RO(memory_top_tier, TOP_TIER),
+};
+
+static struct attribute *memory_tier_attrs[] = {
+ &memory_tiers[0].attr.attr,
+ NULL
+};
+
+static const struct attribute_group memory_tier_attr_group = {
+ .attrs = memory_tier_attrs,
+};
+
static const struct attribute_group *cpu_root_attr_groups[] = {
&memory_root_attr_group,
+ &memory_tier_attr_group,
NULL,
};
As long as we have the ability to see the nodelist, I am good with the
proposal.
-aneesh
