97c910139b
get_tsc_freq uses 'nanosleep' system call to calculate the CPU
frequency. However, 'nanosleep' results in the process getting
un-scheduled. The kernel saves and restores the PMU state. This
ensures that the PMU cycles are not counted towards a sleeping
process. When RTE_ARM_EAL_RDTSC_USE_PMU is defined, this results
in incorrect CPU frequency calculation. This logic is replaced
with generic counter based loop.
Bugzilla ID: 450
Fixes: f91bcbb2d9 ("eal/armv8: use high-resolution cycle counter")
Cc: stable@dpdk.org
Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Reviewed-by: Dharmik Thakkar <dharmik.thakkar@arm.com>
Reviewed-by: Phil Yang <phil.yang@arm.com>
Acked-by: Jerin Jacob <jerinj@marvell.com>
39 lines
966 B
C
39 lines
966 B
C
/* SPDX-License-Identifier: BSD-3-Clause
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* Copyright(c) 2015 Cavium, Inc
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*/
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#include "eal_private.h"
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#include "rte_cycles.h"
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uint64_t
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get_tsc_freq_arch(void)
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{
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#if defined RTE_ARCH_ARM64 && !defined RTE_ARM_EAL_RDTSC_USE_PMU
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return __rte_arm64_cntfrq();
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#elif defined RTE_ARCH_ARM64 && defined RTE_ARM_EAL_RDTSC_USE_PMU
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#define CYC_PER_1MHZ 1E6
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/* Use the generic counter ticks to calculate the PMU
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* cycle frequency.
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*/
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uint64_t ticks;
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uint64_t start_ticks, cur_ticks;
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uint64_t start_pmu_cycles, end_pmu_cycles;
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/* Number of ticks for 1/10 second */
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ticks = __rte_arm64_cntfrq() / 10;
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start_ticks = __rte_arm64_cntvct_precise();
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start_pmu_cycles = rte_rdtsc_precise();
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do {
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cur_ticks = __rte_arm64_cntvct();
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} while ((cur_ticks - start_ticks) < ticks);
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end_pmu_cycles = rte_rdtsc_precise();
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/* Adjust the cycles to next 1Mhz */
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return RTE_ALIGN_MUL_CEIL(end_pmu_cycles - start_pmu_cycles,
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CYC_PER_1MHZ) * 10;
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#else
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return 0;
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#endif
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}
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