When the topology mode is TOPOLOGY_MODE_HW, topology_init_early() already parses the set of socket present on the system.
Use the socket_info to configure the sparsebitmask (sbm) properties for the system - namely the number of sockets and maximum threads in a socket instance. arch_sbm_cpu_instance_id() traverses all socket instances to find a matching CPU which is not optimal but instance ID is only checked when the CPU is coming online. Since this is a rare event, the inefficiency is tolerable. Signed-off-by: K Prateek Nayak <[email protected]> --- Build tested with LKP's s390 randconfig with QEMU cmdline: qemu-system-s390x \ -cpu max \ -smp 2 \ -m 2048 \ -kernel ./arch/s390/boot/vmlinux \ -append "console=ttyAMA0 earlycon ignore_loglevel log_buf_len=10M print_fatal_signals=1 LOGLEVEL=8 sched_debug" \ -nographic Note: Since ctop needs KVM acceleration to emulate TOPOLOGY_MODE_HW, the actual spasemask setting is only build tested at the moment. XXX: Any way around this using cross-compile and QEMU? --- arch/s390/kernel/topology.c | 52 +++++++++++++++++++++++++++++++++++++ 1 file changed, 52 insertions(+) diff --git a/arch/s390/kernel/topology.c b/arch/s390/kernel/topology.c index 1377c6f3f670..80dc51f5ce6f 100644 --- a/arch/s390/kernel/topology.c +++ b/arch/s390/kernel/topology.c @@ -20,6 +20,7 @@ #include <linux/init.h> #include <linux/slab.h> #include <linux/cpu.h> +#include <linux/sbm.h> #include <linux/smp.h> #include <linux/mm.h> #include <linux/nodemask.h> @@ -561,6 +562,55 @@ static int __init detect_polarization(union topology_entry *tle) return tl_core->pp != POLARIZATION_HRZ; } +int arch_sbm_cpu_instance_id(int cpu) +{ + struct mask_info *info = &socket_info; + + /* + * sbm core should not call this if sbm_set_topology() was + * skipped below due to lack of topology information. + */ + if (WARN_ON_ONCE(topology_mode != TOPOLOGY_MODE_HW)) + return -1; + + while (info) { + if (cpumask_test_cpu(cpu, &info->mask)) + return info->id; + info = info->next; + } + + pr_warn_once("socket mapping for CPU%d not found! Mapping to ID 0", cpu); + return 0; +} + +static void __configure_sbm_topology(void) +{ + int num_sbm_instances = 0, max_threads_per_instance = -1; + struct mask_info *info = &socket_info; + + /* + * Consider single package if topology + * information is unavailable. + * + * sbm core will handle the initialization. + */ + if (topology_mode != TOPOLOGY_MODE_HW) + return; + + while (info) { + num_sbm_instances += 1; + max_threads_per_instance = max_t(int, + cpumask_weight(&info->mask), + max_threads_per_instance); + info = info->next; + } + + if (WARN_ON_ONCE(!num_sbm_instances || max_threads_per_instance < 1)) + return; + + sbm_set_topology(num_sbm_instances, max_threads_per_instance); +} + void __init topology_init_early(void) { struct sysinfo_15_1_x *info; @@ -588,6 +638,8 @@ void __init topology_init_early(void) cpumask_set_cpu(0, &cpu_setup_mask); __arch_update_cpu_topology(); __arch_update_dedicated_flag(NULL); + + __configure_sbm_topology(); } static inline int topology_get_mode(int enabled) -- 2.34.1
