Many mfgpt timer interrupts with tickless kernel

[William Cohen]

Chris Ball wrote:
> Hi Will,
> 
>    > I need to put a probe at a higher level to see what is run when the
>    > timer fires. Is there something that can print out what is in the
>    > clockevents_chain?
> 
> Not sure if you're aware that there are timer statistics available:


Chris,

Thanks for the additional details on how to use the timer statistics. Here are a 
few more details one what is going on. Definitely there are additional timers 
being set up for systemtap. Below is what is running when the systemtap 
instrumentation is running on the system. -Will

-bash-3.1# more /proc/timer_stats
Timer Stats Version: v0.1
Sample period: 12.229 s
1221,     0 swapper          tick_nohz_restart_sched_tick (tick_sched_timer)
1221,  1992 insmod           _stp_init_time (__stp_time_timer_callback)
1221,  2006 staprun          schedule_timeout (process_timeout)
1221,  1992 insmod           _stp_transport_init (delayed_work_timer_fn)
  146,     0 swapper          ehci_work (ehci_watchdog)
   19,  1859 sshd             sk_reset_timer (tcp_delack_timer)
   61,  1652 dhcdbd           schedule_timeout (process_timeout)
    5,  1858 sshd             sk_reset_timer (tcp_write_timer)
    7,  1705 NetworkManager   schedule_timeout (process_timeout)
   12,  1895 python           schedule_timeout (process_timeout)
    7,  1850 python           schedule_timeout (process_timeout)
    6,  1625 modprobe         neigh_table_init_no_netlink (neigh_periodic_timer)
    6,  1695 hald-addon-stor  do_nanosleep (hrtimer_wakeup)
    6,  1698 hald-addon-stor  do_nanosleep (hrtimer_wakeup)
    3,     1 init             schedule_timeout (process_timeout)
    6,     1 swapper          queue_delayed_work_on (delayed_work_timer_fn)
    2,  1656 NetworkManager   __netdev_watchdog_up (dev_watchdog)
    3,     1 swapper          neigh_table_init_no_netlink (neigh_periodic_timer)
    2,     0 swapper          page_writeback_init (wb_timer_fn)
5175 total events, 431.423 events/sec