Hello Michael, On Fri, May 18, 2018 at 11:14:04PM +1000, Michael Ellerman wrote: > Gautham R Shenoy <e...@linux.vnet.ibm.com> writes: > ... > >> > @@ -565,7 +615,16 @@ void __init smp_setup_cpu_maps(void) > >> > vdso_data->processorCount = num_present_cpus(); > >> > #endif /* CONFIG_PPC64 */ > >> > > >> > - /* Initialize CPU <=> thread mapping/ > >> > + dn = of_find_node_by_type(NULL, "cpu"); > >> > + if (dn) { > >> > + if (check_for_interleaved_big_core(dn)) { > >> > + has_interleaved_big_core = true; > >> > + pr_info("Detected interleaved big-cores\n"); > >> > >> Is there a runtime way to check this also? If the dmesg buffer overflows, > >> we > >> lose this. > > > > Where do you suggest we put this ? Should it be a part of > > /proc/cpuinfo ? > > Hmm, it'd be nice not to pollute it with more junk. > > Can you just look at the pir files in sysfs?
Sure Michael. I will explore this option. If we add a file called l1cache_thread_group, then the siblings of the big-core that share the L1-cache can be described as follows. # cd /sys/devices/system/cpu # grep . cpu[0-7]/l1cache_thread_group cpu0/l1cache_thread_group:0,2,4,6 cpu1/l1cache_thread_group:1,3,5,7 cpu2/l1cache_thread_group:0,2,4,6 cpu3/l1cache_thread_group:1,3,5,7 cpu4/l1cache_thread_group:0,2,4,6 cpu5/l1cache_thread_group:1,3,5,7 cpu6/l1cache_thread_group:0,2,4,6 cpu7/l1cache_thread_group:1,3,5,7 > > eg. on a normal system: > > # cd /sys/devices/system/cpu > # grep . cpu[0-7]/pir > cpu0/pir:20 > cpu1/pir:21 > cpu2/pir:22 > cpu3/pir:23 > cpu4/pir:24 > cpu5/pir:25 > cpu6/pir:26 > cpu7/pir:27 > > > cheers >