18c2ecf20Sopenharmony_ci========================== 28c2ecf20Sopenharmony_ciARM Cache Coherent Network 38c2ecf20Sopenharmony_ci========================== 48c2ecf20Sopenharmony_ci 58c2ecf20Sopenharmony_ciCCN-504 is a ring-bus interconnect consisting of 11 crosspoints 68c2ecf20Sopenharmony_ci(XPs), with each crosspoint supporting up to two device ports, 78c2ecf20Sopenharmony_ciso nodes (devices) 0 and 1 are connected to crosspoint 0, 88c2ecf20Sopenharmony_cinodes 2 and 3 to crosspoint 1 etc. 98c2ecf20Sopenharmony_ci 108c2ecf20Sopenharmony_ciPMU (perf) driver 118c2ecf20Sopenharmony_ci----------------- 128c2ecf20Sopenharmony_ci 138c2ecf20Sopenharmony_ciThe CCN driver registers a perf PMU driver, which provides 148c2ecf20Sopenharmony_cidescription of available events and configuration options 158c2ecf20Sopenharmony_ciin sysfs, see /sys/bus/event_source/devices/ccn*. 168c2ecf20Sopenharmony_ci 178c2ecf20Sopenharmony_ciThe "format" directory describes format of the config, config1 188c2ecf20Sopenharmony_ciand config2 fields of the perf_event_attr structure. The "events" 198c2ecf20Sopenharmony_cidirectory provides configuration templates for all documented 208c2ecf20Sopenharmony_cievents, that can be used with perf tool. For example "xp_valid_flit" 218c2ecf20Sopenharmony_ciis an equivalent of "type=0x8,event=0x4". Other parameters must be 228c2ecf20Sopenharmony_ciexplicitly specified. 238c2ecf20Sopenharmony_ci 248c2ecf20Sopenharmony_ciFor events originating from device, "node" defines its index. 258c2ecf20Sopenharmony_ci 268c2ecf20Sopenharmony_ciCrosspoint PMU events require "xp" (index), "bus" (bus number) 278c2ecf20Sopenharmony_ciand "vc" (virtual channel ID). 288c2ecf20Sopenharmony_ci 298c2ecf20Sopenharmony_ciCrosspoint watchpoint-based events (special "event" value 0xfe) 308c2ecf20Sopenharmony_cirequire "xp" and "vc" as above plus "port" (device port index), 318c2ecf20Sopenharmony_ci"dir" (transmit/receive direction), comparator values ("cmp_l" 328c2ecf20Sopenharmony_ciand "cmp_h") and "mask", being index of the comparator mask. 338c2ecf20Sopenharmony_ci 348c2ecf20Sopenharmony_ciMasks are defined separately from the event description 358c2ecf20Sopenharmony_ci(due to limited number of the config values) in the "cmp_mask" 368c2ecf20Sopenharmony_cidirectory, with first 8 configurable by user and additional 378c2ecf20Sopenharmony_ci4 hardcoded for the most frequent use cases. 388c2ecf20Sopenharmony_ci 398c2ecf20Sopenharmony_ciCycle counter is described by a "type" value 0xff and does 408c2ecf20Sopenharmony_cinot require any other settings. 418c2ecf20Sopenharmony_ci 428c2ecf20Sopenharmony_ciThe driver also provides a "cpumask" sysfs attribute, which contains 438c2ecf20Sopenharmony_cia single CPU ID, of the processor which will be used to handle all 448c2ecf20Sopenharmony_cithe CCN PMU events. It is recommended that the user space tools 458c2ecf20Sopenharmony_cirequest the events on this processor (if not, the perf_event->cpu value 468c2ecf20Sopenharmony_ciwill be overwritten anyway). In case of this processor being offlined, 478c2ecf20Sopenharmony_cithe events are migrated to another one and the attribute is updated. 488c2ecf20Sopenharmony_ci 498c2ecf20Sopenharmony_ciExample of perf tool use:: 508c2ecf20Sopenharmony_ci 518c2ecf20Sopenharmony_ci / # perf list | grep ccn 528c2ecf20Sopenharmony_ci ccn/cycles/ [Kernel PMU event] 538c2ecf20Sopenharmony_ci <...> 548c2ecf20Sopenharmony_ci ccn/xp_valid_flit,xp=?,port=?,vc=?,dir=?/ [Kernel PMU event] 558c2ecf20Sopenharmony_ci <...> 568c2ecf20Sopenharmony_ci 578c2ecf20Sopenharmony_ci / # perf stat -a -e ccn/cycles/,ccn/xp_valid_flit,xp=1,port=0,vc=1,dir=1/ \ 588c2ecf20Sopenharmony_ci sleep 1 598c2ecf20Sopenharmony_ci 608c2ecf20Sopenharmony_ciThe driver does not support sampling, therefore "perf record" will 618c2ecf20Sopenharmony_cinot work. Per-task (without "-a") perf sessions are not supported. 62