On 2022/12/21 20:37, Leizhen (ThunderTown) wrote:

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I am not familiar with it. But task_cputime() in
kernel/sched/cputime.c looks promising. And there must be
the interface how the user space get this information.
Some is available via /proc/<PID>/... I am not sure
if there is a syscall.

Please, try to investigate the above hints.

Yes, I will. Thanks.

Function task_cputime() works well when CONFIG_VIRT_CPU_ACCOUNTING_GEN=y,
but not when CONFIG_TICK_CPU_ACCOUNTING=y. The latter seems to be based on
tick interrupt sampling, rather than recording timestamps during task switches.

-- 
Regards,
  Zhen Lei