@@ -11,6 +11,7 @@
* for more details.
*/
+#include <linux/acpi.h>
#include <linux/arch_topology.h>
#include <linux/cpu.h>
#include <linux/cpumask.h>
@@ -22,6 +23,7 @@
#include <linux/sched.h>
#include <linux/sched/topology.h>
#include <linux/slab.h>
+#include <linux/smp.h>
#include <linux/string.h>
#include <asm/cpu.h>
@@ -304,6 +306,68 @@ static void __init reset_cpu_topology(void)
}
}
+#ifdef CONFIG_ACPI
+/*
+ * Propagate the topology information of the processor_topology_node tree to the
+ * cpu_topology array.
+ */
+static int __init parse_acpi_topology(void)
+{
+ u64 is_threaded;
+ int is_multisocket;
+ int cpu;
+ int topology_id;
+ /* set a large depth, to hit ACPI_PPTT_PHYSICAL_PACKAGE if one exists */
+ const int max_topo = 0xFF;
+
+ is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK;
+ is_multisocket = acpi_multisocket_count();
+ if (is_multisocket < 0)
+ return is_multisocket;
+
+ for_each_possible_cpu(cpu) {
+ topology_id = setup_acpi_cpu_topology(cpu, 0);
+ if (topology_id < 0)
+ return topology_id;
+
+ if ((is_threaded) && (is_multisocket > 1)) {
+ /* MT per core, and multiple sockets */
+ cpu_topology[cpu].thread_id = topology_id;
+ topology_id = setup_acpi_cpu_topology(cpu, 1);
+ cpu_topology[cpu].core_id = topology_id;
+ topology_id = setup_acpi_cpu_topology(cpu, 2);
+ cpu_topology[cpu].cluster_id = topology_id;
+ topology_id = setup_acpi_cpu_topology(cpu, max_topo);
+ cpu_topology[cpu].package_id = topology_id;
+ } else if (is_threaded) {
+ /* mutltiple threads, but only a single socket */
+ cpu_topology[cpu].thread_id = topology_id;
+ topology_id = setup_acpi_cpu_topology(cpu, 1);
+ cpu_topology[cpu].core_id = topology_id;
+ topology_id = setup_acpi_cpu_topology(cpu, 2);
+ cpu_topology[cpu].cluster_id = topology_id;
+ cpu_topology[cpu].package_id = topology_id;
+ } else {
+ /* no threads, clusters behave like threads */
+ cpu_topology[cpu].thread_id = topology_id;
+ topology_id = setup_acpi_cpu_topology(cpu, 1);
+ cpu_topology[cpu].core_id = topology_id;
+ cpu_topology[cpu].cluster_id = topology_id;
+ topology_id = setup_acpi_cpu_topology(cpu, max_topo);
+ cpu_topology[cpu].package_id = topology_id;
+ }
+ }
+ return 0;
+}
+
+#else
+static int __init parse_acpi_topology(void)
+{
+ /*ACPI kernels should be built with PPTT support*/
+ return -EINVAL;
+}
+#endif
+
void __init init_cpu_topology(void)
{
reset_cpu_topology();
@@ -312,6 +376,8 @@ void __init init_cpu_topology(void)
* Discard anything that was parsed if we hit an error so we
* don't use partial information.
*/
- if (of_have_populated_dt() && parse_dt_topology())
+ if ((!acpi_disabled) && parse_acpi_topology())
+ reset_cpu_topology();
+ else if (of_have_populated_dt() && parse_dt_topology())
reset_cpu_topology();
}
@@ -43,6 +43,8 @@
if (nr_cpus_node(node))
int arch_update_cpu_topology(void);
+int setup_acpi_cpu_topology(unsigned int cpu, int level);
+int acpi_multisocket_count(void);
/* Conform to ACPI 2.0 SLIT distance definitions */
#define LOCAL_DISTANCE 10
Propagate the topology information from the PPTT tree to the cpu_topology array. We can get the thread id, core_id and cluster_id by assuming certain levels of the PPTT tree correspond to those concepts. The package_id is flagged in the tree and can be found by passing an arbitrary large level to setup_acpi_cpu_topology() which terminates its search when it finds an ACPI node flagged as the physical package. If the tree doesn't contain enough levels to represent all of thread/core/cod/package then the package id will be used for the missing levels. Since arm64 machines can have 3 distinct topology levels, and the scheduler only handles sockets/threads well today, we compromise by collapsing into one of three diffrent configurations. These are thread/socket, thread/cluster or cluster/socket depending on whether the machine has threading and multisocket, threading in a single socket, or doesn't have threading. This code is loosely based on a combination of code from: Xiongfeng Wang <wangxiongfeng2@huawei.com> John Garry <john.garry@huawei.com> Jeffrey Hugo <jhugo@codeaurora.org> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> --- arch/arm64/kernel/topology.c | 68 +++++++++++++++++++++++++++++++++++++++++++- include/linux/topology.h | 2 ++ 2 files changed, 69 insertions(+), 1 deletion(-) -- 2.13.5 -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html