> -----Original Message----- > From: Song Bao Hua (Barry Song) > Sent: Tuesday, March 2, 2021 12:00 PM > To: tim.c.chen@xxxxxxxxxxxxxxx; catalin.marinas@xxxxxxx; will@xxxxxxxxxx; > rjw@xxxxxxxxxxxxx; vincent.guittot@xxxxxxxxxx; bp@xxxxxxxxx; > tglx@xxxxxxxxxxxxx; mingo@xxxxxxxxxx; lenb@xxxxxxxxxx; peterz@xxxxxxxxxxxxx; > dietmar.eggemann@xxxxxxx; rostedt@xxxxxxxxxxx; bsegall@xxxxxxxxxx; > mgorman@xxxxxxx > Cc: msys.mizuma@xxxxxxxxx; valentin.schneider@xxxxxxx; > gregkh@xxxxxxxxxxxxxxxxxxx; Jonathan Cameron <jonathan.cameron@xxxxxxxxxx>; > juri.lelli@xxxxxxxxxx; mark.rutland@xxxxxxx; sudeep.holla@xxxxxxx; > aubrey.li@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; > linux-kernel@xxxxxxxxxxxxxxx; linux-acpi@xxxxxxxxxxxxxxx; x86@xxxxxxxxxx; > xuwei (O) <xuwei5@xxxxxxxxxx>; Zengtao (B) <prime.zeng@xxxxxxxxxxxxx>; > guodong.xu@xxxxxxxxxx; yangyicong <yangyicong@xxxxxxxxxx>; Liguozhu (Kenneth) > <liguozhu@xxxxxxxxxxxxx>; linuxarm@xxxxxxxxxxxxx; hpa@xxxxxxxxx; Jonathan > Cameron <jonathan.cameron@xxxxxxxxxx>; Song Bao Hua (Barry Song) > <song.bao.hua@xxxxxxxxxxxxx> > Subject: [RFC PATCH v4 1/3] topology: Represent clusters of CPUs within a die. > > From: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> > > 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 <Jonathan.Cameron@xxxxxxxxxx> > Signed-off-by: Barry Song <song.bao.hua@xxxxxxxxxxxxx> > --- > -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
