diff options
Diffstat (limited to 'lib/librte_eal/common/include/arch/arm/rte_cycles_64.h')
| -rw-r--r-- | lib/librte_eal/common/include/arch/arm/rte_cycles_64.h | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/lib/librte_eal/common/include/arch/arm/rte_cycles_64.h b/lib/librte_eal/common/include/arch/arm/rte_cycles_64.h index 14f26120..867a9468 100644 --- a/lib/librte_eal/common/include/arch/arm/rte_cycles_64.h +++ b/lib/librte_eal/common/include/arch/arm/rte_cycles_64.h @@ -45,6 +45,11 @@ extern "C" { * @return * The time base for this lcore. */ +#ifndef RTE_ARM_EAL_RDTSC_USE_PMU +/** + * This call is portable to any ARMv8 architecture, however, typically + * cntvct_el0 runs at <= 100MHz and it may be imprecise for some tasks. + */ static inline uint64_t rte_rdtsc(void) { @@ -53,6 +58,34 @@ rte_rdtsc(void) asm volatile("mrs %0, cntvct_el0" : "=r" (tsc)); return tsc; } +#else +/** + * This is an alternative method to enable rte_rdtsc() with high resolution + * PMU cycles counter.The cycle counter runs at cpu frequency and this scheme + * uses ARMv8 PMU subsystem to get the cycle counter at userspace, However, + * access to PMU cycle counter from user space is not enabled by default in + * arm64 linux kernel. + * It is possible to enable cycle counter at user space access by configuring + * the PMU from the privileged mode (kernel space). + * + * asm volatile("msr pmintenset_el1, %0" : : "r" ((u64)(0 << 31))); + * asm volatile("msr pmcntenset_el0, %0" :: "r" BIT(31)); + * asm volatile("msr pmuserenr_el0, %0" : : "r"(BIT(0) | BIT(2))); + * asm volatile("mrs %0, pmcr_el0" : "=r" (val)); + * val |= (BIT(0) | BIT(2)); + * isb(); + * asm volatile("msr pmcr_el0, %0" : : "r" (val)); + * + */ +static inline uint64_t +rte_rdtsc(void) +{ + uint64_t tsc; + + asm volatile("mrs %0, pmccntr_el0" : "=r"(tsc)); + return tsc; +} +#endif static inline uint64_t rte_rdtsc_precise(void) |