函数逻辑报告

Linux Kernel

v5.5.9

Brick Technologies Co., Ltd

Source Code:kernel\events\core.c Create Date:2022-07-27 14:50:23
Last Modify:2022-05-20 07:50:19 Copyright©Brick
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函数名称：perf_sample_event_took

函数原型：void perf_sample_event_took(u64 sample_len_ns)

返回类型：void

参数：

类型参数名称
u64sample_len_ns
507  max_len等于READ_ONCE(perf_sample_allowed_ns)
512  如果max_len恒等于0则返回
516  running_len等于Operations for contexts that are safe from preemption/interrupts. These* operations verify that preemption is disabled.(running_sample_length)
517  running_len减等于running_len除perf samples are done in some very critical code paths (NMIs).* If they take too much CPU time, the system can lock up and not* get any real work done. This will drop the sample rate when* we detect that events are taking too long.
518  running_len加等于sample_len_ns
519  __this_cpu_write(running_sample_length, running_len)
526  avg_len等于running_len除perf samples are done in some very critical code paths (NMIs).* If they take too much CPU time, the system can lock up and not* get any real work done. This will drop the sample rate when* we detect that events are taking too long.
527  如果avg_len小于等于max_len则返回
530  __report_avg等于avg_len
531  __report_allowed等于max_len
536  avg_len加等于avg_len除4
537  max等于TICK_NSEC is the time between ticks in nsec assuming SHIFTED_HZ 除100乘sysctl_perf_cpu_time_max_percent
538  如果avg_len小于max则max除等于avg_len
540  否则max等于1
543  WRITE_ONCE(perf_sample_allowed_ns, avg_len)
544  WRITE_ONCE(max_samples_per_tick, max)
546  sysctl_perf_event_sample_rate等于max乘HZ
547  perf_sample_period_ns等于NSEC_PER_SEC除sysctl_perf_event_sample_rate
549  如果非Enqueue the irq work @work on the current CPU 则
550  early_printk("perf: interrupt took too long (%lld > %lld), lowering kernel.perf_event_max_sample_rate to %d\n", __report_avg, __report_allowed, sysctl_perf_event_sample_rate)