ARM64 server chip Kunpeng 920 has 6 or 8 clusters in each NUMA node, and each
cluster has 4 cpus. All clusters share L3 cache data while each cluster has
local L3 tag. On the other hand, each cluster will share some internal system
bus. This means cache is much more affine inside one cluster than across
clusters.
+-----------------------------------+ +---------+
| +------+ +------+ +---------------------------+ |
| | CPU0 | | cpu1 | | +-----------+ | |
| +------+ +------+ | | | | |
| +----+ L3 | | |
| +------+ +------+ cluster | | tag | | |
| | CPU2 | | CPU3 | | | | | |
| +------+ +------+ | +-----------+ | |
| | | |
+-----------------------------------+ | |
+-----------------------------------+ | |
| +------+ +------+ +--------------------------+ |
| | | | | | +-----------+ | |
| +------+ +------+ | | | | |
| | | L3 | | |
| +------+ +------+ +----+ tag | | |
| | | | | | | | | |
| +------+ +------+ | +-----------+ | |
| | | |
+-----------------------------------+ | L3 |
| data |
+-----------------------------------+ | |
| +------+ +------+ | +-----------+ | |
| | | | | | | | | |
| +------+ +------+ +----+ L3 | | |
| | | tag | | |
| +------+ +------+ | | | | |
| | | | | ++ +-----------+ | |
| +------+ +------+ |---------------------------+ |
+-----------------------------------| | |
+-----------------------------------| | |
| +------+ +------+ +---------------------------+ |
| | | | | | +-----------+ | |
| +------+ +------+ | | | | |
| +----+ L3 | | |
| +------+ +------+ | | tag | | |
| | | | | | | | | |
| +------+ +------+ | +-----------+ | |
| | | |
+-----------------------------------+ | |
+-----------------------------------+ | |
| +------+ +------+ +--------------------------+ |
| | | | | | +-----------+ | |
| +------+ +------+ | | | | |
There is a similar need for clustering in x86. Some x86 cores could share L2 caches
that is similar to the cluster in Kupeng 920 (e.g. on Jacobsville there are 6 clusters
of 4 Atom cores, each cluster sharing a separate L2, and 24 cores sharing L3).
Having a sched_domain for clusters will bring two aspects of improvement:
1. spreading unrelated tasks among clusters, which decreases the contention of resources
and improve the throughput.
unrelated tasks might be put randomly without cluster sched_domain:
+-------------------+ +-----------------+
| +----+ +----+ | | |
| |task| |task| | | |
| |1 | |2 | | | |
| +----+ +----+ | | |
| | | |
| cluster1 | | cluster2 |
+-------------------+ +-----------------+
but with cluster sched_domain, they are likely to spread due to LB:
+-------------------+ +-----------------+
| +----+ | | +----+ |
| |task| | | |task| |
| |1 | | | |2 | |
| +----+ | | +----+ |
| | | |
| cluster1 | | cluster2 |
+-------------------+ +-----------------+
2. gathering related tasks within a cluster, which improves the cache affinity of tasks
talking with each other.
Without cluster sched_domain, related tasks might be put randomly. In case task1-8 have
relationship as below:
Task1 wakes up task4
Task2 wakes up task5
Task3 wakes up task6
Task4 wakes up task7
With the tuning of select_idle_cpu() to scan local cluster first, those tasks might
get a chance to be gathered like:
+---------------------------+ +----------------------+
| +----+ +-----+ | | +----+ +-----+ |
| |task| |task | | | |task| |task | |
| |1 | | 4 | | | |2 | |5 | |
| +----+ +-----+ | | +----+ +-----+ |
| | | |
| cluster1 | | cluster2 |
| | | |
| | | |
| +-----+ +------+ | | +-----+ +------+ |
| |task | | task | | | |task | |task | |
| |3 | | 6 | | | |4 | |8 | |
| +-----+ +------+ | | +-----+ +------+ |
+---------------------------+ +----------------------+
Otherwise, the result might be:
+---------------------------+ +----------------------+
| +----+ +-----+ | | +----+ +-----+ |
| |task| |task | | | |task| |task | |
| |1 | | 2 | | | |5 | |6 | |
| +----+ +-----+ | | +----+ +-----+ |
| | | |
| cluster1 | | cluster2 |
| | | |
| | | |
| +-----+ +------+ | | +-----+ +------+ |
| |task | | task | | | |task | |task | |
| |3 | | 4 | | | |7 | |8 | |
| +-----+ +------+ | | +-----+ +------+ |
+---------------------------+ +----------------------+
-v4:
* rebased to tip/sched/core with the latest unified code of select_idle_cpu
* added Tim's patch for x86 Jacobsville
* also added benchmark data of spreading unrelated tasks
* avoided the iteration of sched_domain by moving to static_key(addressing
Vincent's comment
* used acpi_cpu_id for acpi_find_processor_node(addressing Masa's comment)
Barry Song (1):
scheduler: add scheduler level for clusters
Jonathan Cameron (1):
topology: Represent clusters of CPUs within a die.
Tim Chen (1):
scheduler: Add cluster scheduler level for x86
Documentation/admin-guide/cputopology.rst | 26 ++++++++++--
arch/arm64/Kconfig | 7 ++++
arch/arm64/kernel/topology.c | 2 +
arch/x86/Kconfig | 8 ++++
arch/x86/include/asm/smp.h | 7 ++++
arch/x86/include/asm/topology.h | 1 +
arch/x86/kernel/cpu/cacheinfo.c | 1 +
arch/x86/kernel/cpu/common.c | 3 ++
arch/x86/kernel/smpboot.c | 43 +++++++++++++++++++-
drivers/acpi/pptt.c | 63 +++++++++++++++++++++++++++++
drivers/base/arch_topology.c | 14 +++++++
drivers/base/topology.c | 10 +++++
include/linux/acpi.h | 5 +++
include/linux/arch_topology.h | 5 +++
include/linux/sched/cluster.h | 19 +++++++++
include/linux/sched/sd_flags.h | 9 +++++
include/linux/sched/topology.h | 7 ++++
include/linux/topology.h | 13 ++++++
kernel/sched/core.c | 18 +++++++++
kernel/sched/fair.c | 66 ++++++++++++++++++++++++-------
kernel/sched/sched.h | 1 +
kernel/sched/topology.c | 6 +++
22 files changed, 315 insertions(+), 19 deletions(-)
create mode 100644 include/linux/sched/cluster.h
--
1.8.3.1
From: Tim Chen <[email protected]>
There are x86 CPU architectures (e.g. Jacobsville) where L2 cahce
is shared among a cluster of cores instead of being exclusive
to one single core.
To prevent oversubscription of L2 cache, load should be
balanced between such L2 clusters, especially for tasks with
no shared data.
Also with cluster scheduling policy where tasks are woken up
in the same L2 cluster, we will benefit from keeping tasks
related to each other and likely sharing data in the same L2
cluster.
Add CPU masks of CPUs sharing the L2 cache so we can build such
L2 cluster scheduler domain.
Signed-off-by: Tim Chen <[email protected]>
Signed-off-by: Barry Song <[email protected]>
---
arch/x86/Kconfig | 8 ++++++++
arch/x86/include/asm/smp.h | 7 +++++++
arch/x86/include/asm/topology.h | 1 +
arch/x86/kernel/cpu/cacheinfo.c | 1 +
arch/x86/kernel/cpu/common.c | 3 +++
arch/x86/kernel/smpboot.c | 43 ++++++++++++++++++++++++++++++++++++++++-
6 files changed, 62 insertions(+), 1 deletion(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index d3338a8..40110de 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1009,6 +1009,14 @@ config NR_CPUS
This is purely to save memory: each supported CPU adds about 8KB
to the kernel image.
+config SCHED_CLUSTER
+ bool "Cluster scheduler support"
+ default n
+ help
+ Cluster scheduler support improves the CPU scheduler's decision
+ making when dealing with machines that have clusters of CPUs
+ sharing L2 cache. If unsure say N here.
+
config SCHED_SMT
def_bool y if SMP
diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index c0538f8..9cbc4ae 100644
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -16,7 +16,9 @@
DECLARE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_die_map);
/* cpus sharing the last level cache: */
DECLARE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_llc_shared_map);
+DECLARE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_l2c_shared_map);
DECLARE_PER_CPU_READ_MOSTLY(u16, cpu_llc_id);
+DECLARE_PER_CPU_READ_MOSTLY(u16, cpu_l2c_id);
DECLARE_PER_CPU_READ_MOSTLY(int, cpu_number);
static inline struct cpumask *cpu_llc_shared_mask(int cpu)
@@ -24,6 +26,11 @@ static inline struct cpumask *cpu_llc_shared_mask(int cpu)
return per_cpu(cpu_llc_shared_map, cpu);
}
+static inline struct cpumask *cpu_l2c_shared_mask(int cpu)
+{
+ return per_cpu(cpu_l2c_shared_map, cpu);
+}
+
DECLARE_EARLY_PER_CPU_READ_MOSTLY(u16, x86_cpu_to_apicid);
DECLARE_EARLY_PER_CPU_READ_MOSTLY(u32, x86_cpu_to_acpiid);
DECLARE_EARLY_PER_CPU_READ_MOSTLY(u16, x86_bios_cpu_apicid);
diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
index 9239399..2a11ccc 100644
--- a/arch/x86/include/asm/topology.h
+++ b/arch/x86/include/asm/topology.h
@@ -103,6 +103,7 @@ static inline void setup_node_to_cpumask_map(void) { }
#include <asm-generic/topology.h>
extern const struct cpumask *cpu_coregroup_mask(int cpu);
+extern const struct cpumask *cpu_clustergroup_mask(int cpu);
#define topology_logical_package_id(cpu) (cpu_data(cpu).logical_proc_id)
#define topology_physical_package_id(cpu) (cpu_data(cpu).phys_proc_id)
diff --git a/arch/x86/kernel/cpu/cacheinfo.c b/arch/x86/kernel/cpu/cacheinfo.c
index 3ca9be4..0d03a71 100644
--- a/arch/x86/kernel/cpu/cacheinfo.c
+++ b/arch/x86/kernel/cpu/cacheinfo.c
@@ -846,6 +846,7 @@ void init_intel_cacheinfo(struct cpuinfo_x86 *c)
l2 = new_l2;
#ifdef CONFIG_SMP
per_cpu(cpu_llc_id, cpu) = l2_id;
+ per_cpu(cpu_l2c_id, cpu) = l2_id;
#endif
}
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 35ad848..fb08c73 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -78,6 +78,9 @@
/* Last level cache ID of each logical CPU */
DEFINE_PER_CPU_READ_MOSTLY(u16, cpu_llc_id) = BAD_APICID;
+/* L2 cache ID of each logical CPU */
+DEFINE_PER_CPU_READ_MOSTLY(u16, cpu_l2c_id) = BAD_APICID;
+
/* correctly size the local cpu masks */
void __init setup_cpu_local_masks(void)
{
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 02813a7..c85ffa8 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -101,6 +101,8 @@
DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_llc_shared_map);
+DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_l2c_shared_map);
+
/* Per CPU bogomips and other parameters */
DEFINE_PER_CPU_READ_MOSTLY(struct cpuinfo_x86, cpu_info);
EXPORT_PER_CPU_SYMBOL(cpu_info);
@@ -501,6 +503,21 @@ static bool match_llc(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o)
return topology_sane(c, o, "llc");
}
+static bool match_l2c(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o)
+{
+ int cpu1 = c->cpu_index, cpu2 = o->cpu_index;
+
+ /* Do not match if we do not have a valid APICID for cpu: */
+ if (per_cpu(cpu_l2c_id, cpu1) == BAD_APICID)
+ return false;
+
+ /* Do not match if L2 cache id does not match: */
+ if (per_cpu(cpu_l2c_id, cpu1) != per_cpu(cpu_l2c_id, cpu2))
+ return false;
+
+ return topology_sane(c, o, "l2c");
+}
+
/*
* Unlike the other levels, we do not enforce keeping a
* multicore group inside a NUMA node. If this happens, we will
@@ -522,7 +539,7 @@ static bool match_die(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o)
}
-#if defined(CONFIG_SCHED_SMT) || defined(CONFIG_SCHED_MC)
+#if defined(CONFIG_SCHED_SMT) || defined(CONFIG_SCHED_CLUSTER) || defined(CONFIG_SCHED_MC)
static inline int x86_sched_itmt_flags(void)
{
return sysctl_sched_itmt_enabled ? SD_ASYM_PACKING : 0;
@@ -540,12 +557,21 @@ static int x86_smt_flags(void)
return cpu_smt_flags() | x86_sched_itmt_flags();
}
#endif
+#ifdef CONFIG_SCHED_CLUSTER
+static int x86_cluster_flags(void)
+{
+ return cpu_cluster_flags() | x86_sched_itmt_flags();
+}
+#endif
#endif
static struct sched_domain_topology_level x86_numa_in_package_topology[] = {
#ifdef CONFIG_SCHED_SMT
{ cpu_smt_mask, x86_smt_flags, SD_INIT_NAME(SMT) },
#endif
+#ifdef CONFIG_SCHED_CLUSTER
+ { cpu_clustergroup_mask, x86_cluster_flags, SD_INIT_NAME(CLS) },
+#endif
#ifdef CONFIG_SCHED_MC
{ cpu_coregroup_mask, x86_core_flags, SD_INIT_NAME(MC) },
#endif
@@ -556,6 +582,9 @@ static int x86_smt_flags(void)
#ifdef CONFIG_SCHED_SMT
{ cpu_smt_mask, x86_smt_flags, SD_INIT_NAME(SMT) },
#endif
+#ifdef CONFIG_SCHED_CLUSTER
+ { cpu_clustergroup_mask, x86_cluster_flags, SD_INIT_NAME(CLS) },
+#endif
#ifdef CONFIG_SCHED_MC
{ cpu_coregroup_mask, x86_core_flags, SD_INIT_NAME(MC) },
#endif
@@ -583,6 +612,7 @@ void set_cpu_sibling_map(int cpu)
if (!has_mp) {
cpumask_set_cpu(cpu, topology_sibling_cpumask(cpu));
cpumask_set_cpu(cpu, cpu_llc_shared_mask(cpu));
+ cpumask_set_cpu(cpu, cpu_l2c_shared_mask(cpu));
cpumask_set_cpu(cpu, topology_core_cpumask(cpu));
cpumask_set_cpu(cpu, topology_die_cpumask(cpu));
c->booted_cores = 1;
@@ -598,6 +628,8 @@ void set_cpu_sibling_map(int cpu)
if ((i == cpu) || (has_mp && match_llc(c, o)))
link_mask(cpu_llc_shared_mask, cpu, i);
+ if ((i == cpu) || (has_mp && match_l2c(c, o)))
+ link_mask(cpu_l2c_shared_mask, cpu, i);
}
/*
@@ -649,6 +681,11 @@ const struct cpumask *cpu_coregroup_mask(int cpu)
return cpu_llc_shared_mask(cpu);
}
+const struct cpumask *cpu_clustergroup_mask(int cpu)
+{
+ return cpu_l2c_shared_mask(cpu);
+}
+
static void impress_friends(void)
{
int cpu;
@@ -1332,6 +1369,7 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
zalloc_cpumask_var(&per_cpu(cpu_core_map, i), GFP_KERNEL);
zalloc_cpumask_var(&per_cpu(cpu_die_map, i), GFP_KERNEL);
zalloc_cpumask_var(&per_cpu(cpu_llc_shared_map, i), GFP_KERNEL);
+ zalloc_cpumask_var(&per_cpu(cpu_l2c_shared_map, i), GFP_KERNEL);
}
/*
@@ -1556,7 +1594,10 @@ static void remove_siblinginfo(int cpu)
cpumask_clear_cpu(cpu, topology_sibling_cpumask(sibling));
for_each_cpu(sibling, cpu_llc_shared_mask(cpu))
cpumask_clear_cpu(cpu, cpu_llc_shared_mask(sibling));
+ for_each_cpu(sibling, cpu_l2c_shared_mask(cpu))
+ cpumask_clear_cpu(cpu, cpu_l2c_shared_mask(sibling));
cpumask_clear(cpu_llc_shared_mask(cpu));
+ cpumask_clear(cpu_l2c_shared_mask(cpu));
cpumask_clear(topology_sibling_cpumask(cpu));
cpumask_clear(topology_core_cpumask(cpu));
cpumask_clear(topology_die_cpumask(cpu));
--
1.8.3.1
From: Jonathan Cameron <[email protected]>
Both ACPI and DT provide the ability to describe additional layers of
topology between that of individual cores and higher level constructs
such as the level at which the last level cache is shared.
In ACPI this can be represented in PPTT as a Processor Hierarchy
Node Structure [1] that is the parent of the CPU cores and in turn
has a parent Processor Hierarchy Nodes Structure representing
a higher level of topology.
For example Kunpeng 920 has 6 or 8 clusters in each NUMA node, and each
cluster has 4 cpus. All clusters share L3 cache data, but each cluster
has local L3 tag. On the other hand, each clusters will share some
internal system bus.
+-----------------------------------+ +---------+
| +------+ +------+ +---------------------------+ |
| | CPU0 | | cpu1 | | +-----------+ | |
| +------+ +------+ | | | | |
| +----+ L3 | | |
| +------+ +------+ cluster | | tag | | |
| | CPU2 | | CPU3 | | | | | |
| +------+ +------+ | +-----------+ | |
| | | |
+-----------------------------------+ | |
+-----------------------------------+ | |
| +------+ +------+ +--------------------------+ |
| | | | | | +-----------+ | |
| +------+ +------+ | | | | |
| | | L3 | | |
| +------+ +------+ +----+ tag | | |
| | | | | | | | | |
| +------+ +------+ | +-----------+ | |
| | | |
+-----------------------------------+ | L3 |
| data |
+-----------------------------------+ | |
| +------+ +------+ | +-----------+ | |
| | | | | | | | | |
| +------+ +------+ +----+ L3 | | |
| | | tag | | |
| +------+ +------+ | | | | |
| | | | | ++ +-----------+ | |
| +------+ +------+ |---------------------------+ |
+-----------------------------------| | |
+-----------------------------------| | |
| +------+ +------+ +---------------------------+ |
| | | | | | +-----------+ | |
| +------+ +------+ | | | | |
| +----+ L3 | | |
| +------+ +------+ | | tag | | |
| | | | | | | | | |
| +------+ +------+ | +-----------+ | |
| | | |
+-----------------------------------+ | |
+-----------------------------------+ | |
| +------+ +------+ +--------------------------+ |
| | | | | | +-----------+ | |
| +------+ +------+ | | | | |
| | | L3 | | |
| +------+ +------+ +---+ tag | | |
| | | | | | | | | |
| +------+ +------+ | +-----------+ | |
| | | |
+-----------------------------------+ | |
+-----------------------------------+ ++ |
| +------+ +------+ +--------------------------+ |
| | | | | | +-----------+ | |
| +------+ +------+ | | | | |
| | | L3 | | |
| +------+ +------+ +--+ tag | | |
| | | | | | | | | |
| +------+ +------+ | +-----------+ | |
| | +---------+
+-----------------------------------+
That means the cost to transfer ownership of a cacheline between CPUs
within a cluster is lower than between CPUs in different clusters on
the same die. Hence, it can make sense to tell the scheduler to use
the cache affinity of the cluster to make better decision on thread
migration.
This patch simply exposes this information to userspace libraries
like hwloc by providing cluster_cpus and related sysfs attributes.
PoC of HWLOC support at [2].
Note this patch only handle the ACPI case.
Special consideration is needed for SMT processors, where it is
necessary to move 2 levels up the hierarchy from the leaf nodes
(thus skipping the processor core level).
Currently the ID provided is the offset of the Processor
Hierarchy Nodes Structure within PPTT. Whilst this is unique
it is not terribly elegant so alternative suggestions welcome.
Note that arm64 / ACPI does not provide any means of identifying
a die level in the topology but that may be unrelate to the cluster
level.
[1] ACPI Specification 6.3 - section 5.2.29.1 processor hierarchy node
structure (Type 0)
[2] https://github.com/hisilicon/hwloc/tree/linux-cluster
Signed-off-by: Jonathan Cameron <[email protected]>
Signed-off-by: Barry Song <[email protected]>
---
-v4:
* used acpi_cpu_id for acpi_find_processor_node(addressing Masa's comment)
Documentation/admin-guide/cputopology.rst | 26 +++++++++++--
arch/arm64/kernel/topology.c | 2 +
drivers/acpi/pptt.c | 63 +++++++++++++++++++++++++++++++
drivers/base/arch_topology.c | 14 +++++++
drivers/base/topology.c | 10 +++++
include/linux/acpi.h | 5 +++
include/linux/arch_topology.h | 5 +++
include/linux/topology.h | 6 +++
8 files changed, 127 insertions(+), 4 deletions(-)
diff --git a/Documentation/admin-guide/cputopology.rst b/Documentation/admin-guide/cputopology.rst
index b90dafc..f9d3745 100644
--- a/Documentation/admin-guide/cputopology.rst
+++ b/Documentation/admin-guide/cputopology.rst
@@ -24,6 +24,12 @@ core_id:
identifier (rather than the kernel's). The actual value is
architecture and platform dependent.
+cluster_id:
+
+ the Cluster ID of cpuX. Typically it is the hardware platform's
+ identifier (rather than the kernel's). The actual value is
+ architecture and platform dependent.
+
book_id:
the book ID of cpuX. Typically it is the hardware platform's
@@ -56,6 +62,14 @@ package_cpus_list:
human-readable list of CPUs sharing the same physical_package_id.
(deprecated name: "core_siblings_list")
+cluster_cpus:
+
+ internal kernel map of CPUs within the same cluster.
+
+cluster_cpus_list:
+
+ human-readable list of CPUs within the same cluster.
+
die_cpus:
internal kernel map of CPUs within the same die.
@@ -96,11 +110,13 @@ these macros in include/asm-XXX/topology.h::
#define topology_physical_package_id(cpu)
#define topology_die_id(cpu)
+ #define topology_cluster_id(cpu)
#define topology_core_id(cpu)
#define topology_book_id(cpu)
#define topology_drawer_id(cpu)
#define topology_sibling_cpumask(cpu)
#define topology_core_cpumask(cpu)
+ #define topology_cluster_cpumask(cpu)
#define topology_die_cpumask(cpu)
#define topology_book_cpumask(cpu)
#define topology_drawer_cpumask(cpu)
@@ -116,10 +132,12 @@ not defined by include/asm-XXX/topology.h:
1) topology_physical_package_id: -1
2) topology_die_id: -1
-3) topology_core_id: 0
-4) topology_sibling_cpumask: just the given CPU
-5) topology_core_cpumask: just the given CPU
-6) topology_die_cpumask: just the given CPU
+3) topology_cluster_id: -1
+4) topology_core_id: 0
+5) topology_sibling_cpumask: just the given CPU
+6) topology_core_cpumask: just the given CPU
+7) topology_cluster_cpumask: just the given CPU
+8) topology_die_cpumask: just the given CPU
For architectures that don't support books (CONFIG_SCHED_BOOK) there are no
default definitions for topology_book_id() and topology_book_cpumask().
diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
index f6faa69..fe076b3 100644
--- a/arch/arm64/kernel/topology.c
+++ b/arch/arm64/kernel/topology.c
@@ -103,6 +103,8 @@ int __init parse_acpi_topology(void)
cpu_topology[cpu].thread_id = -1;
cpu_topology[cpu].core_id = topology_id;
}
+ topology_id = find_acpi_cpu_topology_cluster(cpu);
+ cpu_topology[cpu].cluster_id = topology_id;
topology_id = find_acpi_cpu_topology_package(cpu);
cpu_topology[cpu].package_id = topology_id;
diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c
index 4ae9335..11f8b02 100644
--- a/drivers/acpi/pptt.c
+++ b/drivers/acpi/pptt.c
@@ -737,6 +737,69 @@ int find_acpi_cpu_topology_package(unsigned int cpu)
}
/**
+ * find_acpi_cpu_topology_cluster() - Determine a unique CPU cluster value
+ * @cpu: Kernel logical CPU number
+ *
+ * Determine a topology unique cluster ID for the given CPU/thread.
+ * This ID can then be used to group peers, which will have matching ids.
+ *
+ * The cluster, if present is the level of topology above CPUs. In a
+ * multi-thread CPU, it will be the level above the CPU, not the thread.
+ * It may not exist in single CPU systems. In simple multi-CPU systems,
+ * it may be equal to the package topology level.
+ *
+ * Return: -ENOENT if the PPTT doesn't exist, the CPU cannot be found
+ * or there is no toplogy level above the CPU..
+ * Otherwise returns a value which represents the package for this CPU.
+ */
+
+int find_acpi_cpu_topology_cluster(unsigned int cpu)
+{
+ struct acpi_table_header *table;
+ acpi_status status;
+ struct acpi_pptt_processor *cpu_node, *cluster_node;
+ u32 acpi_cpu_id;
+ int retval;
+ int is_thread;
+
+ status = acpi_get_table(ACPI_SIG_PPTT, 0, &table);
+ if (ACPI_FAILURE(status)) {
+ acpi_pptt_warn_missing();
+ return -ENOENT;
+ }
+
+ acpi_cpu_id = get_acpi_id_for_cpu(cpu);
+ cpu_node = acpi_find_processor_node(table, acpi_cpu_id);
+ if (cpu_node == NULL || !cpu_node->parent) {
+ retval = -ENOENT;
+ goto put_table;
+ }
+
+ is_thread = cpu_node->flags & ACPI_PPTT_ACPI_PROCESSOR_IS_THREAD;
+ cluster_node = fetch_pptt_node(table, cpu_node->parent);
+ if (cluster_node == NULL) {
+ retval = -ENOENT;
+ goto put_table;
+ }
+ if (is_thread) {
+ if (!cluster_node->parent) {
+ retval = -ENOENT;
+ goto put_table;
+ }
+ cluster_node = fetch_pptt_node(table, cluster_node->parent);
+ if (cluster_node == NULL) {
+ retval = -ENOENT;
+ goto put_table;
+ }
+ }
+ retval = ACPI_PTR_DIFF(cluster_node, table);
+put_table:
+ acpi_put_table(table);
+
+ return retval;
+}
+
+/**
* find_acpi_cpu_topology_hetero_id() - Get a core architecture tag
* @cpu: Kernel logical CPU number
*
diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index de8587c..3079232 100644
--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c
@@ -506,6 +506,11 @@ const struct cpumask *cpu_coregroup_mask(int cpu)
return core_mask;
}
+const struct cpumask *cpu_clustergroup_mask(int cpu)
+{
+ return &cpu_topology[cpu].cluster_sibling;
+}
+
void update_siblings_masks(unsigned int cpuid)
{
struct cpu_topology *cpu_topo, *cpuid_topo = &cpu_topology[cpuid];
@@ -523,6 +528,11 @@ void update_siblings_masks(unsigned int cpuid)
if (cpuid_topo->package_id != cpu_topo->package_id)
continue;
+ if (cpuid_topo->cluster_id == cpu_topo->cluster_id) {
+ cpumask_set_cpu(cpu, &cpuid_topo->cluster_sibling);
+ cpumask_set_cpu(cpuid, &cpu_topo->cluster_sibling);
+ }
+
cpumask_set_cpu(cpuid, &cpu_topo->core_sibling);
cpumask_set_cpu(cpu, &cpuid_topo->core_sibling);
@@ -541,6 +551,9 @@ static void clear_cpu_topology(int cpu)
cpumask_clear(&cpu_topo->llc_sibling);
cpumask_set_cpu(cpu, &cpu_topo->llc_sibling);
+ cpumask_clear(&cpu_topo->cluster_sibling);
+ cpumask_set_cpu(cpu, &cpu_topo->cluster_sibling);
+
cpumask_clear(&cpu_topo->core_sibling);
cpumask_set_cpu(cpu, &cpu_topo->core_sibling);
cpumask_clear(&cpu_topo->thread_sibling);
@@ -571,6 +584,7 @@ void remove_cpu_topology(unsigned int cpu)
cpumask_clear_cpu(cpu, topology_core_cpumask(sibling));
for_each_cpu(sibling, topology_sibling_cpumask(cpu))
cpumask_clear_cpu(cpu, topology_sibling_cpumask(sibling));
+
for_each_cpu(sibling, topology_llc_cpumask(cpu))
cpumask_clear_cpu(cpu, topology_llc_cpumask(sibling));
diff --git a/drivers/base/topology.c b/drivers/base/topology.c
index 4d254fc..7157ac0 100644
--- a/drivers/base/topology.c
+++ b/drivers/base/topology.c
@@ -46,6 +46,9 @@
define_id_show_func(die_id);
static DEVICE_ATTR_RO(die_id);
+define_id_show_func(cluster_id);
+static DEVICE_ATTR_RO(cluster_id);
+
define_id_show_func(core_id);
static DEVICE_ATTR_RO(core_id);
@@ -61,6 +64,10 @@
static DEVICE_ATTR_RO(core_siblings);
static DEVICE_ATTR_RO(core_siblings_list);
+define_siblings_show_func(cluster_cpus, cluster_cpumask);
+static DEVICE_ATTR_RO(cluster_cpus);
+static DEVICE_ATTR_RO(cluster_cpus_list);
+
define_siblings_show_func(die_cpus, die_cpumask);
static DEVICE_ATTR_RO(die_cpus);
static DEVICE_ATTR_RO(die_cpus_list);
@@ -88,6 +95,7 @@
static struct attribute *default_attrs[] = {
&dev_attr_physical_package_id.attr,
&dev_attr_die_id.attr,
+ &dev_attr_cluster_id.attr,
&dev_attr_core_id.attr,
&dev_attr_thread_siblings.attr,
&dev_attr_thread_siblings_list.attr,
@@ -95,6 +103,8 @@
&dev_attr_core_cpus_list.attr,
&dev_attr_core_siblings.attr,
&dev_attr_core_siblings_list.attr,
+ &dev_attr_cluster_cpus.attr,
+ &dev_attr_cluster_cpus_list.attr,
&dev_attr_die_cpus.attr,
&dev_attr_die_cpus_list.attr,
&dev_attr_package_cpus.attr,
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 053bf05..161196a 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -1332,6 +1332,7 @@ static inline int lpit_read_residency_count_address(u64 *address)
#ifdef CONFIG_ACPI_PPTT
int acpi_pptt_cpu_is_thread(unsigned int cpu);
int find_acpi_cpu_topology(unsigned int cpu, int level);
+int find_acpi_cpu_topology_cluster(unsigned int cpu);
int find_acpi_cpu_topology_package(unsigned int cpu);
int find_acpi_cpu_topology_hetero_id(unsigned int cpu);
int find_acpi_cpu_cache_topology(unsigned int cpu, int level);
@@ -1344,6 +1345,10 @@ static inline int find_acpi_cpu_topology(unsigned int cpu, int level)
{
return -EINVAL;
}
+static inline int find_acpi_cpu_topology_cluster(unsigned int cpu)
+{
+ return -EINVAL;
+}
static inline int find_acpi_cpu_topology_package(unsigned int cpu)
{
return -EINVAL;
diff --git a/include/linux/arch_topology.h b/include/linux/arch_topology.h
index 0f6cd6b..987c7ea 100644
--- a/include/linux/arch_topology.h
+++ b/include/linux/arch_topology.h
@@ -49,10 +49,12 @@ void topology_set_thermal_pressure(const struct cpumask *cpus,
struct cpu_topology {
int thread_id;
int core_id;
+ int cluster_id;
int package_id;
int llc_id;
cpumask_t thread_sibling;
cpumask_t core_sibling;
+ cpumask_t cluster_sibling;
cpumask_t llc_sibling;
};
@@ -60,13 +62,16 @@ struct cpu_topology {
extern struct cpu_topology cpu_topology[NR_CPUS];
#define topology_physical_package_id(cpu) (cpu_topology[cpu].package_id)
+#define topology_cluster_id(cpu) (cpu_topology[cpu].cluster_id)
#define topology_core_id(cpu) (cpu_topology[cpu].core_id)
#define topology_core_cpumask(cpu) (&cpu_topology[cpu].core_sibling)
#define topology_sibling_cpumask(cpu) (&cpu_topology[cpu].thread_sibling)
+#define topology_cluster_cpumask(cpu) (&cpu_topology[cpu].cluster_sibling)
#define topology_llc_cpumask(cpu) (&cpu_topology[cpu].llc_sibling)
void init_cpu_topology(void);
void store_cpu_topology(unsigned int cpuid);
const struct cpumask *cpu_coregroup_mask(int cpu);
+const struct cpumask *cpu_clustergroup_mask(int cpu);
void update_siblings_masks(unsigned int cpu);
void remove_cpu_topology(unsigned int cpuid);
void reset_cpu_topology(void);
diff --git a/include/linux/topology.h b/include/linux/topology.h
index 7634cd7..80d27d7 100644
--- a/include/linux/topology.h
+++ b/include/linux/topology.h
@@ -186,6 +186,9 @@ static inline int cpu_to_mem(int cpu)
#ifndef topology_die_id
#define topology_die_id(cpu) ((void)(cpu), -1)
#endif
+#ifndef topology_cluster_id
+#define topology_cluster_id(cpu) ((void)(cpu), -1)
+#endif
#ifndef topology_core_id
#define topology_core_id(cpu) ((void)(cpu), 0)
#endif
@@ -195,6 +198,9 @@ static inline int cpu_to_mem(int cpu)
#ifndef topology_core_cpumask
#define topology_core_cpumask(cpu) cpumask_of(cpu)
#endif
+#ifndef topology_cluster_cpumask
+#define topology_cluster_cpumask(cpu) cpumask_of(cpu)
+#endif
#ifndef topology_die_cpumask
#define topology_die_cpumask(cpu) cpumask_of(cpu)
#endif
--
1.8.3.1
> -----Original Message-----
> From: Song Bao Hua (Barry Song)
> Sent: Tuesday, March 2, 2021 12:00 PM
> To: [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]
> Cc: [email protected]; [email protected];
> [email protected]; Jonathan Cameron <[email protected]>;
> [email protected]; [email protected]; [email protected];
> [email protected]; [email protected];
> [email protected]; [email protected]; [email protected];
> xuwei (O) <[email protected]>; Zengtao (B) <[email protected]>;
> [email protected]; yangyicong <[email protected]>; Liguozhu (Kenneth)
> <[email protected]>; [email protected]; [email protected]; Jonathan
> Cameron <[email protected]>; Song Bao Hua (Barry Song)
> <[email protected]>
> Subject: [RFC PATCH v4 1/3] topology: Represent clusters of CPUs within a die.
>
> From: Jonathan Cameron <[email protected]>
>
> Both ACPI and DT provide the ability to describe additional layers of
> topology between that of individual cores and higher level constructs
> such as the level at which the last level cache is shared.
> In ACPI this can be represented in PPTT as a Processor Hierarchy
> Node Structure [1] that is the parent of the CPU cores and in turn
> has a parent Processor Hierarchy Nodes Structure representing
> a higher level of topology.
>
> For example Kunpeng 920 has 6 or 8 clusters in each NUMA node, and each
> cluster has 4 cpus. All clusters share L3 cache data, but each cluster
> has local L3 tag. On the other hand, each clusters will share some
> internal system bus.
>
> +-----------------------------------+ +---------+
> | +------+ +------+ +---------------------------+ |
> | | CPU0 | | cpu1 | | +-----------+ | |
> | +------+ +------+ | | | | |
> | +----+ L3 | | |
> | +------+ +------+ cluster | | tag | | |
> | | CPU2 | | CPU3 | | | | | |
> | +------+ +------+ | +-----------+ | |
> | | | |
> +-----------------------------------+ | |
> +-----------------------------------+ | |
> | +------+ +------+ +--------------------------+ |
> | | | | | | +-----------+ | |
> | +------+ +------+ | | | | |
> | | | L3 | | |
> | +------+ +------+ +----+ tag | | |
> | | | | | | | | | |
> | +------+ +------+ | +-----------+ | |
> | | | |
> +-----------------------------------+ | L3 |
> | data |
> +-----------------------------------+ | |
> | +------+ +------+ | +-----------+ | |
> | | | | | | | | | |
> | +------+ +------+ +----+ L3 | | |
> | | | tag | | |
> | +------+ +------+ | | | | |
> | | | | | ++ +-----------+ | |
> | +------+ +------+ |---------------------------+ |
> +-----------------------------------| | |
> +-----------------------------------| | |
> | +------+ +------+ +---------------------------+ |
> | | | | | | +-----------+ | |
> | +------+ +------+ | | | | |
> | +----+ L3 | | |
> | +------+ +------+ | | tag | | |
> | | | | | | | | | |
> | +------+ +------+ | +-----------+ | |
> | | | |
> +-----------------------------------+ | |
> +-----------------------------------+ | |
> | +------+ +------+ +--------------------------+ |
> | | | | | | +-----------+ | |
> | +------+ +------+ | | | | |
> | | | L3 | | |
> | +------+ +------+ +---+ tag | | |
> | | | | | | | | | |
> | +------+ +------+ | +-----------+ | |
> | | | |
> +-----------------------------------+ | |
> +-----------------------------------+ ++ |
> | +------+ +------+ +--------------------------+ |
> | | | | | | +-----------+ | |
> | +------+ +------+ | | | | |
> | | | L3 | | |
> | +------+ +------+ +--+ tag | | |
> | | | | | | | | | |
> | +------+ +------+ | +-----------+ | |
> | | +---------+
> +-----------------------------------+
>
> That means the cost to transfer ownership of a cacheline between CPUs
> within a cluster is lower than between CPUs in different clusters on
> the same die. Hence, it can make sense to tell the scheduler to use
> the cache affinity of the cluster to make better decision on thread
> migration.
>
> This patch simply exposes this information to userspace libraries
> like hwloc by providing cluster_cpus and related sysfs attributes.
> PoC of HWLOC support at [2].
>
> Note this patch only handle the ACPI case.
>
> Special consideration is needed for SMT processors, where it is
> necessary to move 2 levels up the hierarchy from the leaf nodes
> (thus skipping the processor core level).
>
> Currently the ID provided is the offset of the Processor
> Hierarchy Nodes Structure within PPTT. Whilst this is unique
> it is not terribly elegant so alternative suggestions welcome.
>
> Note that arm64 / ACPI does not provide any means of identifying
> a die level in the topology but that may be unrelate to the cluster
> level.
>
> [1] ACPI Specification 6.3 - section 5.2.29.1 processor hierarchy node
> structure (Type 0)
> [2] https://github.com/hisilicon/hwloc/tree/linux-cluster
>
> Signed-off-by: Jonathan Cameron <[email protected]>
> Signed-off-by: Barry Song <[email protected]>
> ---
> -v4:
> * used acpi_cpu_id for acpi_find_processor_node(addressing Masa's comment)
>
> Documentation/admin-guide/cputopology.rst | 26 +++++++++++--
> arch/arm64/kernel/topology.c | 2 +
> drivers/acpi/pptt.c | 63 +++++++++++++++++++++++++++++++
> drivers/base/arch_topology.c | 14 +++++++
> drivers/base/topology.c | 10 +++++
> include/linux/acpi.h | 5 +++
> include/linux/arch_topology.h | 5 +++
> include/linux/topology.h | 6 +++
> 8 files changed, 127 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/admin-guide/cputopology.rst
> b/Documentation/admin-guide/cputopology.rst
> index b90dafc..f9d3745 100644
> --- a/Documentation/admin-guide/cputopology.rst
> +++ b/Documentation/admin-guide/cputopology.rst
> @@ -24,6 +24,12 @@ core_id:
> identifier (rather than the kernel's). The actual value is
> architecture and platform dependent.
>
> +cluster_id:
> +
> + the Cluster ID of cpuX. Typically it is the hardware platform's
> + identifier (rather than the kernel's). The actual value is
> + architecture and platform dependent.
> +
> book_id:
>
> the book ID of cpuX. Typically it is the hardware platform's
> @@ -56,6 +62,14 @@ package_cpus_list:
> human-readable list of CPUs sharing the same physical_package_id.
> (deprecated name: "core_siblings_list")
>
> +cluster_cpus:
> +
> + internal kernel map of CPUs within the same cluster.
> +
> +cluster_cpus_list:
> +
> + human-readable list of CPUs within the same cluster.
> +
> die_cpus:
>
> internal kernel map of CPUs within the same die.
> @@ -96,11 +110,13 @@ these macros in include/asm-XXX/topology.h::
>
> #define topology_physical_package_id(cpu)
> #define topology_die_id(cpu)
> + #define topology_cluster_id(cpu)
> #define topology_core_id(cpu)
> #define topology_book_id(cpu)
> #define topology_drawer_id(cpu)
> #define topology_sibling_cpumask(cpu)
> #define topology_core_cpumask(cpu)
> + #define topology_cluster_cpumask(cpu)
> #define topology_die_cpumask(cpu)
> #define topology_book_cpumask(cpu)
> #define topology_drawer_cpumask(cpu)
> @@ -116,10 +132,12 @@ not defined by include/asm-XXX/topology.h:
>
> 1) topology_physical_package_id: -1
> 2) topology_die_id: -1
> -3) topology_core_id: 0
> -4) topology_sibling_cpumask: just the given CPU
> -5) topology_core_cpumask: just the given CPU
> -6) topology_die_cpumask: just the given CPU
> +3) topology_cluster_id: -1
> +4) topology_core_id: 0
> +5) topology_sibling_cpumask: just the given CPU
> +6) topology_core_cpumask: just the given CPU
> +7) topology_cluster_cpumask: just the given CPU
> +8) topology_die_cpumask: just the given CPU
>
> For architectures that don't support books (CONFIG_SCHED_BOOK) there are no
> default definitions for topology_book_id() and topology_book_cpumask().
> diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
> index f6faa69..fe076b3 100644
> --- a/arch/arm64/kernel/topology.c
> +++ b/arch/arm64/kernel/topology.c
> @@ -103,6 +103,8 @@ int __init parse_acpi_topology(void)
> cpu_topology[cpu].thread_id = -1;
> cpu_topology[cpu].core_id = topology_id;
> }
> + topology_id = find_acpi_cpu_topology_cluster(cpu);
> + cpu_topology[cpu].cluster_id = topology_id;
> topology_id = find_acpi_cpu_topology_package(cpu);
> cpu_topology[cpu].package_id = topology_id;
>
> diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c
> index 4ae9335..11f8b02 100644
> --- a/drivers/acpi/pptt.c
> +++ b/drivers/acpi/pptt.c
> @@ -737,6 +737,69 @@ int find_acpi_cpu_topology_package(unsigned int cpu)
> }
>
> /**
> + * find_acpi_cpu_topology_cluster() - Determine a unique CPU cluster value
> + * @cpu: Kernel logical CPU number
> + *
> + * Determine a topology unique cluster ID for the given CPU/thread.
> + * This ID can then be used to group peers, which will have matching ids.
> + *
> + * The cluster, if present is the level of topology above CPUs. In a
> + * multi-thread CPU, it will be the level above the CPU, not the thread.
> + * It may not exist in single CPU systems. In simple multi-CPU systems,
> + * it may be equal to the package topology level.
> + *
> + * Return: -ENOENT if the PPTT doesn't exist, the CPU cannot be found
> + * or there is no toplogy level above the CPU..
> + * Otherwise returns a value which represents the package for this CPU.
> + */
> +
> +int find_acpi_cpu_topology_cluster(unsigned int cpu)
> +{
> + struct acpi_table_header *table;
> + acpi_status status;
> + struct acpi_pptt_processor *cpu_node, *cluster_node;
> + u32 acpi_cpu_id;
> + int retval;
> + int is_thread;
> +
> + status = acpi_get_table(ACPI_SIG_PPTT, 0, &table);
> + if (ACPI_FAILURE(status)) {
> + acpi_pptt_warn_missing();
> + return -ENOENT;
> + }
> +
> + acpi_cpu_id = get_acpi_id_for_cpu(cpu);
> + cpu_node = acpi_find_processor_node(table, acpi_cpu_id);
> + if (cpu_node == NULL || !cpu_node->parent) {
> + retval = -ENOENT;
> + goto put_table;
> + }
> +
> + is_thread = cpu_node->flags & ACPI_PPTT_ACPI_PROCESSOR_IS_THREAD;
> + cluster_node = fetch_pptt_node(table, cpu_node->parent);
> + if (cluster_node == NULL) {
> + retval = -ENOENT;
> + goto put_table;
> + }
> + if (is_thread) {
> + if (!cluster_node->parent) {
> + retval = -ENOENT;
> + goto put_table;
> + }
> + cluster_node = fetch_pptt_node(table, cluster_node->parent);
> + if (cluster_node == NULL) {
> + retval = -ENOENT;
> + goto put_table;
> + }
> + }
> + retval = ACPI_PTR_DIFF(cluster_node, table);
> +put_table:
> + acpi_put_table(table);
> +
> + return retval;
> +}
> +
> +/**
> * find_acpi_cpu_topology_hetero_id() - Get a core architecture tag
> * @cpu: Kernel logical CPU number
> *
> diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
> index de8587c..3079232 100644
> --- a/drivers/base/arch_topology.c
> +++ b/drivers/base/arch_topology.c
> @@ -506,6 +506,11 @@ const struct cpumask *cpu_coregroup_mask(int cpu)
> return core_mask;
> }
>
> +const struct cpumask *cpu_clustergroup_mask(int cpu)
> +{
> + return &cpu_topology[cpu].cluster_sibling;
> +}
> +
> void update_siblings_masks(unsigned int cpuid)
> {
> struct cpu_topology *cpu_topo, *cpuid_topo = &cpu_topology[cpuid];
> @@ -523,6 +528,11 @@ void update_siblings_masks(unsigned int cpuid)
> if (cpuid_topo->package_id != cpu_topo->package_id)
> continue;
>
> + if (cpuid_topo->cluster_id == cpu_topo->cluster_id) {
> + cpumask_set_cpu(cpu, &cpuid_topo->cluster_sibling);
> + cpumask_set_cpu(cpuid, &cpu_topo->cluster_sibling);
> + }
> +
I am seeing a machine without cluster is getting cluster,
so I guess we need the below:
diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index 3079232ed8ed..ccd4b3b5cc6f 100644
--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c
@@ -528,7 +528,8 @@ void update_siblings_masks(unsigned int cpuid)
if (cpuid_topo->package_id != cpu_topo->package_id)
continue;
- if (cpuid_topo->cluster_id == cpu_topo->cluster_id) {
+ if (cpuid_topo->cluster_id == cpu_topo->cluster_id &&
+ cpu_topo->cluster_id != -1) {
cpumask_set_cpu(cpu, &cpuid_topo->cluster_sibling);
cpumask_set_cpu(cpuid, &cpu_topo->cluster_sibling);
}
@@ -568,6 +569,7 @@ void __init reset_cpu_topology(void)
struct cpu_topology *cpu_topo = &cpu_topology[cpu];
cpu_topo->thread_id = -1;
+ cpu_topo->cluster_id = -1;
cpu_topo->core_id = -1;
cpu_topo->package_id = -1;
cpu_topo->llc_id = -1;
Hi Jonathan, thoughts?
Thanks
Barry
On Mon, 15 Mar 2021 03:11:06 +0000
"Song Bao Hua (Barry Song)" <[email protected]> wrote:
> > -----Original Message-----
> > From: Song Bao Hua (Barry Song)
> > Sent: Tuesday, March 2, 2021 12:00 PM
> > To: [email protected]; [email protected]; [email protected];
> > [email protected]; [email protected]; [email protected];
> > [email protected]; [email protected]; [email protected]; [email protected];
> > [email protected]; [email protected]; [email protected];
> > [email protected]
> > Cc: [email protected]; [email protected];
> > [email protected]; Jonathan Cameron <[email protected]>;
> > [email protected]; [email protected]; [email protected];
> > [email protected]; [email protected];
> > [email protected]; [email protected]; [email protected];
> > xuwei (O) <[email protected]>; Zengtao (B) <[email protected]>;
> > [email protected]; yangyicong <[email protected]>; Liguozhu (Kenneth)
> > <[email protected]>; [email protected]; [email protected]; Jonathan
> > Cameron <[email protected]>; Song Bao Hua (Barry Song)
> > <[email protected]>
> > Subject: [RFC PATCH v4 1/3] topology: Represent clusters of CPUs within a die.
> >
> > From: Jonathan Cameron <[email protected]>
> >
> > Both ACPI and DT provide the ability to describe additional layers of
> > topology between that of individual cores and higher level constructs
> > such as the level at which the last level cache is shared.
> > In ACPI this can be represented in PPTT as a Processor Hierarchy
> > Node Structure [1] that is the parent of the CPU cores and in turn
> > has a parent Processor Hierarchy Nodes Structure representing
> > a higher level of topology.
> >
> > For example Kunpeng 920 has 6 or 8 clusters in each NUMA node, and each
> > cluster has 4 cpus. All clusters share L3 cache data, but each cluster
> > has local L3 tag. On the other hand, each clusters will share some
> > internal system bus.
> >
> > +-----------------------------------+ +---------+
> > | +------+ +------+ +---------------------------+ |
> > | | CPU0 | | cpu1 | | +-----------+ | |
> > | +------+ +------+ | | | | |
> > | +----+ L3 | | |
> > | +------+ +------+ cluster | | tag | | |
> > | | CPU2 | | CPU3 | | | | | |
> > | +------+ +------+ | +-----------+ | |
> > | | | |
> > +-----------------------------------+ | |
> > +-----------------------------------+ | |
> > | +------+ +------+ +--------------------------+ |
> > | | | | | | +-----------+ | |
> > | +------+ +------+ | | | | |
> > | | | L3 | | |
> > | +------+ +------+ +----+ tag | | |
> > | | | | | | | | | |
> > | +------+ +------+ | +-----------+ | |
> > | | | |
> > +-----------------------------------+ | L3 |
> > | data |
> > +-----------------------------------+ | |
> > | +------+ +------+ | +-----------+ | |
> > | | | | | | | | | |
> > | +------+ +------+ +----+ L3 | | |
> > | | | tag | | |
> > | +------+ +------+ | | | | |
> > | | | | | ++ +-----------+ | |
> > | +------+ +------+ |---------------------------+ |
> > +-----------------------------------| | |
> > +-----------------------------------| | |
> > | +------+ +------+ +---------------------------+ |
> > | | | | | | +-----------+ | |
> > | +------+ +------+ | | | | |
> > | +----+ L3 | | |
> > | +------+ +------+ | | tag | | |
> > | | | | | | | | | |
> > | +------+ +------+ | +-----------+ | |
> > | | | |
> > +-----------------------------------+ | |
> > +-----------------------------------+ | |
> > | +------+ +------+ +--------------------------+ |
> > | | | | | | +-----------+ | |
> > | +------+ +------+ | | | | |
> > | | | L3 | | |
> > | +------+ +------+ +---+ tag | | |
> > | | | | | | | | | |
> > | +------+ +------+ | +-----------+ | |
> > | | | |
> > +-----------------------------------+ | |
> > +-----------------------------------+ ++ |
> > | +------+ +------+ +--------------------------+ |
> > | | | | | | +-----------+ | |
> > | +------+ +------+ | | | | |
> > | | | L3 | | |
> > | +------+ +------+ +--+ tag | | |
> > | | | | | | | | | |
> > | +------+ +------+ | +-----------+ | |
> > | | +---------+
> > +-----------------------------------+
> >
> > That means the cost to transfer ownership of a cacheline between CPUs
> > within a cluster is lower than between CPUs in different clusters on
> > the same die. Hence, it can make sense to tell the scheduler to use
> > the cache affinity of the cluster to make better decision on thread
> > migration.
> >
> > This patch simply exposes this information to userspace libraries
> > like hwloc by providing cluster_cpus and related sysfs attributes.
> > PoC of HWLOC support at [2].
> >
> > Note this patch only handle the ACPI case.
> >
> > Special consideration is needed for SMT processors, where it is
> > necessary to move 2 levels up the hierarchy from the leaf nodes
> > (thus skipping the processor core level).
> >
> > Currently the ID provided is the offset of the Processor
> > Hierarchy Nodes Structure within PPTT. Whilst this is unique
> > it is not terribly elegant so alternative suggestions welcome.
> >
> > Note that arm64 / ACPI does not provide any means of identifying
> > a die level in the topology but that may be unrelate to the cluster
> > level.
> >
> > [1] ACPI Specification 6.3 - section 5.2.29.1 processor hierarchy node
> > structure (Type 0)
> > [2] https://github.com/hisilicon/hwloc/tree/linux-cluster
> >
> > Signed-off-by: Jonathan Cameron <[email protected]>
> > Signed-off-by: Barry Song <[email protected]>
> > ---
> > -v4:
> > * used acpi_cpu_id for acpi_find_processor_node(addressing Masa's comment)
> >
> > Documentation/admin-guide/cputopology.rst | 26 +++++++++++--
> > arch/arm64/kernel/topology.c | 2 +
> > drivers/acpi/pptt.c | 63 +++++++++++++++++++++++++++++++
> > drivers/base/arch_topology.c | 14 +++++++
> > drivers/base/topology.c | 10 +++++
> > include/linux/acpi.h | 5 +++
> > include/linux/arch_topology.h | 5 +++
> > include/linux/topology.h | 6 +++
> > 8 files changed, 127 insertions(+), 4 deletions(-)
> >
> > diff --git a/Documentation/admin-guide/cputopology.rst
> > b/Documentation/admin-guide/cputopology.rst
> > index b90dafc..f9d3745 100644
> > --- a/Documentation/admin-guide/cputopology.rst
> > +++ b/Documentation/admin-guide/cputopology.rst
> > @@ -24,6 +24,12 @@ core_id:
> > identifier (rather than the kernel's). The actual value is
> > architecture and platform dependent.
> >
> > +cluster_id:
> > +
> > + the Cluster ID of cpuX. Typically it is the hardware platform's
> > + identifier (rather than the kernel's). The actual value is
> > + architecture and platform dependent.
> > +
> > book_id:
> >
> > the book ID of cpuX. Typically it is the hardware platform's
> > @@ -56,6 +62,14 @@ package_cpus_list:
> > human-readable list of CPUs sharing the same physical_package_id.
> > (deprecated name: "core_siblings_list")
> >
> > +cluster_cpus:
> > +
> > + internal kernel map of CPUs within the same cluster.
> > +
> > +cluster_cpus_list:
> > +
> > + human-readable list of CPUs within the same cluster.
> > +
> > die_cpus:
> >
> > internal kernel map of CPUs within the same die.
> > @@ -96,11 +110,13 @@ these macros in include/asm-XXX/topology.h::
> >
> > #define topology_physical_package_id(cpu)
> > #define topology_die_id(cpu)
> > + #define topology_cluster_id(cpu)
> > #define topology_core_id(cpu)
> > #define topology_book_id(cpu)
> > #define topology_drawer_id(cpu)
> > #define topology_sibling_cpumask(cpu)
> > #define topology_core_cpumask(cpu)
> > + #define topology_cluster_cpumask(cpu)
> > #define topology_die_cpumask(cpu)
> > #define topology_book_cpumask(cpu)
> > #define topology_drawer_cpumask(cpu)
> > @@ -116,10 +132,12 @@ not defined by include/asm-XXX/topology.h:
> >
> > 1) topology_physical_package_id: -1
> > 2) topology_die_id: -1
> > -3) topology_core_id: 0
> > -4) topology_sibling_cpumask: just the given CPU
> > -5) topology_core_cpumask: just the given CPU
> > -6) topology_die_cpumask: just the given CPU
> > +3) topology_cluster_id: -1
> > +4) topology_core_id: 0
> > +5) topology_sibling_cpumask: just the given CPU
> > +6) topology_core_cpumask: just the given CPU
> > +7) topology_cluster_cpumask: just the given CPU
> > +8) topology_die_cpumask: just the given CPU
> >
> > For architectures that don't support books (CONFIG_SCHED_BOOK) there are no
> > default definitions for topology_book_id() and topology_book_cpumask().
> > diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
> > index f6faa69..fe076b3 100644
> > --- a/arch/arm64/kernel/topology.c
> > +++ b/arch/arm64/kernel/topology.c
> > @@ -103,6 +103,8 @@ int __init parse_acpi_topology(void)
> > cpu_topology[cpu].thread_id = -1;
> > cpu_topology[cpu].core_id = topology_id;
> > }
> > + topology_id = find_acpi_cpu_topology_cluster(cpu);
> > + cpu_topology[cpu].cluster_id = topology_id;
> > topology_id = find_acpi_cpu_topology_package(cpu);
> > cpu_topology[cpu].package_id = topology_id;
> >
> > diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c
> > index 4ae9335..11f8b02 100644
> > --- a/drivers/acpi/pptt.c
> > +++ b/drivers/acpi/pptt.c
> > @@ -737,6 +737,69 @@ int find_acpi_cpu_topology_package(unsigned int cpu)
> > }
> >
> > /**
> > + * find_acpi_cpu_topology_cluster() - Determine a unique CPU cluster value
> > + * @cpu: Kernel logical CPU number
> > + *
> > + * Determine a topology unique cluster ID for the given CPU/thread.
> > + * This ID can then be used to group peers, which will have matching ids.
> > + *
> > + * The cluster, if present is the level of topology above CPUs. In a
> > + * multi-thread CPU, it will be the level above the CPU, not the thread.
> > + * It may not exist in single CPU systems. In simple multi-CPU systems,
> > + * it may be equal to the package topology level.
> > + *
> > + * Return: -ENOENT if the PPTT doesn't exist, the CPU cannot be found
> > + * or there is no toplogy level above the CPU..
> > + * Otherwise returns a value which represents the package for this CPU.
> > + */
> > +
> > +int find_acpi_cpu_topology_cluster(unsigned int cpu)
> > +{
> > + struct acpi_table_header *table;
> > + acpi_status status;
> > + struct acpi_pptt_processor *cpu_node, *cluster_node;
> > + u32 acpi_cpu_id;
> > + int retval;
> > + int is_thread;
> > +
> > + status = acpi_get_table(ACPI_SIG_PPTT, 0, &table);
> > + if (ACPI_FAILURE(status)) {
> > + acpi_pptt_warn_missing();
> > + return -ENOENT;
> > + }
> > +
> > + acpi_cpu_id = get_acpi_id_for_cpu(cpu);
> > + cpu_node = acpi_find_processor_node(table, acpi_cpu_id);
> > + if (cpu_node == NULL || !cpu_node->parent) {
> > + retval = -ENOENT;
> > + goto put_table;
> > + }
> > +
> > + is_thread = cpu_node->flags & ACPI_PPTT_ACPI_PROCESSOR_IS_THREAD;
> > + cluster_node = fetch_pptt_node(table, cpu_node->parent);
> > + if (cluster_node == NULL) {
> > + retval = -ENOENT;
> > + goto put_table;
> > + }
> > + if (is_thread) {
> > + if (!cluster_node->parent) {
> > + retval = -ENOENT;
> > + goto put_table;
> > + }
> > + cluster_node = fetch_pptt_node(table, cluster_node->parent);
> > + if (cluster_node == NULL) {
> > + retval = -ENOENT;
> > + goto put_table;
> > + }
> > + }
> > + retval = ACPI_PTR_DIFF(cluster_node, table);
> > +put_table:
> > + acpi_put_table(table);
> > +
> > + return retval;
> > +}
> > +
> > +/**
> > * find_acpi_cpu_topology_hetero_id() - Get a core architecture tag
> > * @cpu: Kernel logical CPU number
> > *
> > diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
> > index de8587c..3079232 100644
> > --- a/drivers/base/arch_topology.c
> > +++ b/drivers/base/arch_topology.c
> > @@ -506,6 +506,11 @@ const struct cpumask *cpu_coregroup_mask(int cpu)
> > return core_mask;
> > }
> >
> > +const struct cpumask *cpu_clustergroup_mask(int cpu)
> > +{
> > + return &cpu_topology[cpu].cluster_sibling;
> > +}
> > +
> > void update_siblings_masks(unsigned int cpuid)
> > {
> > struct cpu_topology *cpu_topo, *cpuid_topo = &cpu_topology[cpuid];
> > @@ -523,6 +528,11 @@ void update_siblings_masks(unsigned int cpuid)
> > if (cpuid_topo->package_id != cpu_topo->package_id)
> > continue;
> >
> > + if (cpuid_topo->cluster_id == cpu_topo->cluster_id) {
> > + cpumask_set_cpu(cpu, &cpuid_topo->cluster_sibling);
> > + cpumask_set_cpu(cpuid, &cpu_topo->cluster_sibling);
> > + }
> > +
>
> I am seeing a machine without cluster is getting cluster,
> so I guess we need the below:
Makes sense and is inline with the docs above.
Thanks,
Jonathan
>
> diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
> index 3079232ed8ed..ccd4b3b5cc6f 100644
> --- a/drivers/base/arch_topology.c
> +++ b/drivers/base/arch_topology.c
> @@ -528,7 +528,8 @@ void update_siblings_masks(unsigned int cpuid)
> if (cpuid_topo->package_id != cpu_topo->package_id)
> continue;
>
> - if (cpuid_topo->cluster_id == cpu_topo->cluster_id) {
> + if (cpuid_topo->cluster_id == cpu_topo->cluster_id &&
> + cpu_topo->cluster_id != -1) {
> cpumask_set_cpu(cpu, &cpuid_topo->cluster_sibling);
> cpumask_set_cpu(cpuid, &cpu_topo->cluster_sibling);
> }
> @@ -568,6 +569,7 @@ void __init reset_cpu_topology(void)
> struct cpu_topology *cpu_topo = &cpu_topology[cpu];
>
> cpu_topo->thread_id = -1;
> + cpu_topo->cluster_id = -1;
> cpu_topo->core_id = -1;
> cpu_topo->package_id = -1;
> cpu_topo->llc_id = -1;
>
> Hi Jonathan, thoughts?
>
> Thanks
> Barry
>