From: Qizhi Zhang <zhangqizhi3@h-partners.com> perf: arm_pmuv3: Factor out PMCCNTR_EL0 use conditions and Don't use PMCCNTR_EL0 on SMT cores PMCCNTR_EL0 is preferred for counting CPU_CYCLES under certain conditions. Factor out the condition check to a separate function for further extension. Add documents for better understanding. No functional changes intended. PU_CYCLES is expected to count the logical CPU (PE) clock. Currently it's preferred to use PMCCNTR_EL0 for counting CPU_CYCLES, but it'll count processor clock rather than the PE clock (ARM DDI0487 L.b D13.1.3) if one of the SMT siblings is not idle on a multi-threaded implementation. So don't use it on SMT cores. Yicong Yang (2): perf: arm_pmuv3: Factor out PMCCNTR_EL0 use conditions perf: arm_pmuv3: Don't use PMCCNTR_EL0 on SMT cores drivers/perf/arm_pmu.c | 3 +++ drivers/perf/arm_pmuv3.c | 32 ++++++++++++++++++++++++++++++-- include/linux/arch_topology.h | 11 +++++++++++ include/linux/perf/arm_pmu.h | 1 + 4 files changed, 45 insertions(+), 2 deletions(-) -- 2.33.0