Function report

Linux Kernel

v5.5.9

Brick Technologies Co., Ltd

Source Code:kernel\events\core.c Create Date:2022-07-28 13:35:33
Last Modify:2022-05-20 07:50:19 Copyright©Brick
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Name:calc_timer_values

Proto:static void calc_timer_values(struct perf_event *event, u64 *now, u64 *enabled, u64 *running)

Type:void

Parameter:

TypeParameterName
struct perf_event *event
u64 *now
u64 *enabled
u64 *running
5428  now = perf_clock()
5429  ctx_time = shadow_ctx_time + now
5430  __perf_update_times(event, ctx_time, enabled, running)
Caller
NameDescribe
perf_event_update_userpageCallers need to ensure there can be no nesting of this function, otherwise* the seqlock logic goes bad. We can not serialize this because the arch* code calls this from NMI context.
perf_output_readXXX PERF_SAMPLE_READ vs inherited events seems difficult.* The problem is that its both hard and excessively expensive to iterate the* child list, not to mention that its impossible to IPI the children running* on another CPU, from interrupt/NMI context.