On Wed, Apr 06, 2016 at 08:30:25AM -0700, Guenter Roeck wrote: > On Wed, Apr 06, 2016 at 03:44:11PM +0800, Huang Rui wrote: > > > > +static void do_read_registers_on_cu(void *_data) > > +{ > > + struct fam15h_power_data *data = _data; > > + int cpu, cu; > > + > > + cpu = smp_processor_id(); > > + > > Is this function now defined in non-SMP code ? If so, can you point me to the > patch or branch introducing it ? It doesn't seem to be in mainline or in -next > unless I am missing it. > In include/linux/smp.h #else /* !SMP */ static inline void smp_send_stop(void) { } /* * These macros fold the SMP functionality into a single CPU system */ #define raw_smp_processor_id() 0 ... /* * smp_processor_id(): get the current CPU ID. * * if DEBUG_PREEMPT is enabled then we check whether it is * used in a preemption-safe way. (smp_processor_id() is safe * if it's used in a preemption-off critical section, or in * a thread that is bound to the current CPU.) * * NOTE: raw_smp_processor_id() is for internal use only * (smp_processor_id() is the preferred variant), but in rare * instances it might also be used to turn off false positives * (i.e. smp_processor_id() use that the debugging code reports but * which use for some reason is legal). Don't use this to hack around * the warning message, as your code might not work under PREEMPT. */ #ifdef CONFIG_DEBUG_PREEMPT extern unsigned int debug_smp_processor_id(void); # define smp_processor_id() debug_smp_processor_id() #else # define smp_processor_id() raw_smp_processor_id() #endif Actually smp_processor_id() should returns 0 if we disable CONFIG_SMP. > > + /* > > + * With the new x86 topology modelling, cpu core id actually > > + * is compute unit id. > > + */ > > + cu = cpu_data(cpu).cpu_core_id; > > + > > + rdmsrl_safe(MSR_F15H_CU_PWR_ACCUMULATOR, &data->cu_acc_power[cu]); > > +} > > + > > +/* > > + * This function is only able to be called when CPUID > > + * Fn8000_0007:EDX[12] is set. > > + */ > > +static int read_registers(struct fam15h_power_data *data) > > +{ > > + int this_cpu, ret, cpu; > > + int core, this_core; > > + cpumask_var_t mask; > > + > > + ret = zalloc_cpumask_var(&mask, GFP_KERNEL); > > + if (!ret) > > + return -ENOMEM; > > + > > + get_online_cpus(); > > + this_cpu = smp_processor_id(); > > + > > + /* > > + * Choose the first online core of each compute unit, and then > > + * read their MSR value of power and ptsc in a single IPI, > > + * because the MSR value of CPU core represent the compute > > + * unit's. > > + */ > > + core = -1; > > + > > + for_each_online_cpu(cpu) { > > + this_core = topology_core_id(cpu); > > + > > + if (this_core == core) > > + continue; > > + > > + core = this_core; > > + > Sorry if I missed some context - is it guaranteed that all cores in the same > compute unit are returned next to each other from for_each_online_cpu() ? > Yes, there is a documentation which introduced from v4.6-rc2: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=f7be8610bca88e59dd2fd5d98fcbc5031ef0e079 - topology_core_id(); The ID of the core to which a thread belongs. It is also printed in /proc/cpuinfo "core_id." ... AMD nomenclature for CMT systems: [node 0] -> [Compute Unit 0] -> [Compute Unit Core 0] -> Linux CPU 0 -> [Compute Unit Core 1] -> Linux CPU 1 -> [Compute Unit 1] -> [Compute Unit Core 0] -> Linux CPU 2 -> [Compute Unit Core 1] -> Linux CPU 3 ray@hr-ub:~/tip$ cat /proc/cpuinfo | grep "core id" core id : 0 core id : 0 core id : 1 core id : 1 "this_core" here actually means the [Compute Unit] id which current [Compute Unit Core] belongs to. And "cpu" here means the [Compute Unit Core]. Thanks, Rui -- To unsubscribe from this list: send the line "unsubscribe linux-hwmon" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html