[PATCH] arch_topology: support parsing cluster_id from DT

From: Qing Wang
Date: Thu May 05 2022 - 04:36:10 EST


From: Wang Qing <wangqing@xxxxxxxx>

Use nested cluster structures in DT to support describing multi-level
cluster topologies.

Notice: the clusters describing in DT currently are not physical
boundaries, since changing "cluster" to "socket" is too involved and error
prone, this patch will not have any effect on one-level cluster topo, but
can support the mutil-level cluster topo to support CLUSTER_SCHED.

Signed-off-by: Wang Qing <wangqing@xxxxxxxx>
---
drivers/base/arch_topology.c | 25 +++++++++++++++++--------
1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index 1d6636ebaac5..f2ea8113d619 100644
--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c
@@ -491,7 +491,7 @@ static int __init get_cpu_for_node(struct device_node *node)
}

static int __init parse_core(struct device_node *core, int package_id,
- int core_id)
+ int cluster_id, int core_id)
{
char name[20];
bool leaf = true;
@@ -507,6 +507,7 @@ static int __init parse_core(struct device_node *core, int package_id,
cpu = get_cpu_for_node(t);
if (cpu >= 0) {
cpu_topology[cpu].package_id = package_id;
+ cpu_topology[cpu].cluster_id = cluster_id;
cpu_topology[cpu].core_id = core_id;
cpu_topology[cpu].thread_id = i;
} else if (cpu != -ENODEV) {
@@ -528,6 +529,7 @@ static int __init parse_core(struct device_node *core, int package_id,
}

cpu_topology[cpu].package_id = package_id;
+ cpu_topology[cpu].cluster_id = cluster_id;
cpu_topology[cpu].core_id = core_id;
} else if (leaf && cpu != -ENODEV) {
pr_err("%pOF: Can't get CPU for leaf core\n", core);
@@ -544,13 +546,15 @@ static int __init parse_cluster(struct device_node *cluster, int depth)
bool has_cores = false;
struct device_node *c;
static int package_id __initdata;
+ static int cluster_id __initdata;
int core_id = 0;
int i, ret;

/*
- * First check for child clusters; we currently ignore any
- * information about the nesting of clusters and present the
- * scheduler with a flat list of them.
+ * nesting of clusters :
+ * level 1: package_id
+ * level 2: cluster_id
+ * level 3+: ignore
*/
i = 0;
do {
@@ -559,6 +563,14 @@ static int __init parse_cluster(struct device_node *cluster, int depth)
if (c) {
leaf = false;
ret = parse_cluster(c, depth + 1);
+ if (depth == 0) {
+ package_id++;
+ cluster_id = 0;
+ } else if (depth == 1)
+ cluster_id++;
+ else
+ pr_err("Ignore nested clusters with more than two levels!\n");
+
of_node_put(c);
if (ret != 0)
return ret;
@@ -582,7 +594,7 @@ static int __init parse_cluster(struct device_node *cluster, int depth)
}

if (leaf) {
- ret = parse_core(c, package_id, core_id++);
+ ret = parse_core(c, package_id, cluster_id, core_id++);
} else {
pr_err("%pOF: Non-leaf cluster with core %s\n",
cluster, name);
@@ -599,9 +611,6 @@ static int __init parse_cluster(struct device_node *cluster, int depth)
if (leaf && !has_cores)
pr_warn("%pOF: empty cluster\n", cluster);

- if (leaf)
- package_id++;
-
return 0;
}

--
2.7.4