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Re: [Xen-devel] [PATCH] remove blocked time accounting from xen "clockchip"



On 10/20/11 16:35, Laszlo Ersek wrote:

I'm convinced the patch is correct, and only the commit message might
need a small fix (mentioning cpu_idle()).

I forgot to say that I also added counters to xen_timer_interrupt(), account_idle_ticks() (called from cpu_idle()), and the idle time branch of account_process_tick(). (The last one is reached from xen_timer_interrupt() via event_handler == &tick_nohz_handler, after highres=off was passed). When the VM was left alone, they were increasing in strict lock-step.

account_idle_time()

  <- account_idle_ticks()
    <- tick_nohz_restart_sched_tick()
      <- cpu_idle()

  <- account_process_tick()
    <- update_process_times()
      <- tick_nohz_handler() [highres=off]
        <- xen_timer_interrupt()

      <- (tick_periodic())
      <- (tick_sched_timer())

The timer interrupt appears to kick cpu_idle(), and the latter accounts for the time spent idly.

Laszlo

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