On Fri, 2006-05-12 at 12:20 +0200, Ingo Molnar wrote:
> * Andrew Morton <[email protected]> wrote:
>
> > Makes my machine hang early during the startup of init.
> >
> > The last process to pass through close_file() is `hostname', presuably
> > parented by init. `hostname' exits then everything stops. init is
> > left sleeping in select().
> >
> > All very strange.
>
> weird. This really shouldnt cause a hang - i think there must be a bug
> hiding elsewhere, this cond_resched() ought to be fine.
>
Ingo,
Would this be the latency it fixes? (seen with 2.6.16):
preemption latency trace v1.1.5 on 2.6.16
--------------------------------------------------------------------
latency: 9313 us, #12766/12766, CPU#0 | (M:rt VP:0, KP:0, SP:0 HP:0)
-----------------
| task: jackd-26580 (uid:1000 nice:0 policy:1 rt_prio:80)
-----------------
_------=> CPU#
/ _-----=> irqs-off
| / _----=> need-resched
|| / _---=> hardirq/softirq
||| / _--=> preempt-depth
|||| /
||||| delay
cmd pid ||||| time | caller
\ / ||||| \ | /
ldconfig-26779 0d.h5 0us : __trace_start_sched_wakeup
(try_to_wake_up)
ldconfig-26779 0d.h5 1us : __trace_start_sched_wakeup <<...>-26580>
(13 0)
ldconfig-26779 0d.h. 2us : kill_fasync (snd_pcm_period_elapsed)
ldconfig-26779 0d.h. 3us : snd_emu10k1_voice_intr_ack
(snd_emu10k1_interrupt)
ldconfig-26779 0d.h. 5us+: snd_emu10k1_ptr_read
(snd_emu10k1_interrupt)
ldconfig-26779 0d.h. 8us+: snd_emu10k1_ptr_read
(snd_emu10k1_interrupt)
ldconfig-26779 0d.h1 12us : note_interrupt (__do_IRQ)
ldconfig-26779 0d.h1 13us : end_8259A_irq (__do_IRQ)
ldconfig-26779 0d.h1 13us : enable_8259A_irq (end_8259A_irq)
ldconfig-26779 0dnh2 15us : irq_exit (do_IRQ)
ldconfig-26779 0dn.2 16us < (2097760)
ldconfig-26779 0dn.2 17us : preempt_schedule (find_get_page)
ldconfig-26779 0dn.2 18us : put_page (free_file)
ldconfig-26779 0dn.2 18us : free_file (unmap_vmas)
ldconfig-26779 0dn.2 19us : find_get_page (free_file)
ldconfig-26779 0dn.3 20us : radix_tree_lookup (find_get_page)
ldconfig-26779 0dn.2 20us : preempt_schedule (find_get_page)
ldconfig-26779 0dn.2 21us : put_page (free_file)
ldconfig-26779 0dn.2 22us : free_file (unmap_vmas)
ldconfig-26779 0dn.2 22us : find_get_page (free_file)
ldconfig-26779 0dn.3 23us : radix_tree_lookup (find_get_page)
ldconfig-26779 0dn.2 24us : preempt_schedule (find_get_page)
ldconfig-26779 0dn.2 24us : put_page (free_file)
ldconfig-26779 0dn.2 25us : free_file (unmap_vmas)
ldconfig-26779 0dn.2 26us : find_get_page (free_file)
ldconfig-26779 0dn.3 26us : radix_tree_lookup (find_get_page)
ldconfig-26779 0dn.2 27us : preempt_schedule (find_get_page)
(...)
ldconfig-26779 0dn.2 9256us : put_page (free_file)
ldconfig-26779 0dn.2 9256us : free_file (unmap_vmas)
ldconfig-26779 0dn.2 9257us : find_get_page (free_file)
ldconfig-26779 0dn.3 9258us : radix_tree_lookup (find_get_page)
ldconfig-26779 0dn.2 9259us : preempt_schedule (find_get_page)
ldconfig-26779 0dn.2 9259us : put_page (free_file)
ldconfig-26779 0dn.2 9260us : free_file (unmap_vmas)
ldconfig-26779 0dn.2 9261us : find_get_page (free_file)
ldconfig-26779 0dn.3 9261us : radix_tree_lookup (find_get_page)
ldconfig-26779 0dn.2 9262us : preempt_schedule (find_get_page)
ldconfig-26779 0dn.2 9263us : put_page (free_file)
ldconfig-26779 0dn.1 9263us+: preempt_schedule (unmap_vmas)
ldconfig-26779 0dn.1 9266us : free_pgtables (unmap_region)
ldconfig-26779 0dn.1 9267us : anon_vma_unlink (free_pgtables)
ldconfig-26779 0dn.1 9269us : unlink_file_vma (free_pgtables)
ldconfig-26779 0dn.2 9269us : __remove_shared_vm_struct
(unlink_file_vma)
ldconfig-26779 0dn.2 9270us : vma_prio_tree_remove
(__remove_shared_vm_struct)
ldconfig-26779 0dn.2 9271us : prio_tree_remove (vma_prio_tree_remove)
ldconfig-26779 0dn.1 9273us : preempt_schedule (unlink_file_vma)
ldconfig-26779 0dn.1 9274us : free_pgd_range (free_pgtables)
ldconfig-26779 0dn.1 9275us : free_page_and_swap_cache (free_pgd_range)
ldconfig-26779 0dn.1 9276us : put_page (free_page_and_swap_cache)
ldconfig-26779 0dn.1 9277us : __page_cache_release (put_page)
ldconfig-26779 0dn.1 9278us : preempt_schedule (__page_cache_release)
ldconfig-26779 0dn.1 9279us : free_hot_page (__page_cache_release)
ldconfig-26779 0dn.1 9279us : free_hot_cold_page (free_hot_page)
ldconfig-26779 0dn.2 9280us : __mod_page_state_offset
(free_hot_cold_page)
ldconfig-26779 0dn.1 9281us : preempt_schedule (free_hot_cold_page)
ldconfig-26779 0dn.1 9282us : mod_page_state_offset (free_pgd_range)
ldconfig-26779 0dn.1 9283us : free_page_and_swap_cache (free_pgd_range)
ldconfig-26779 0dn.1 9284us : put_page (free_page_and_swap_cache)
ldconfig-26779 0dn.1 9285us : __page_cache_release (put_page)
ldconfig-26779 0dn.1 9285us : preempt_schedule (__page_cache_release)
ldconfig-26779 0dn.1 9286us : free_hot_page (__page_cache_release)
ldconfig-26779 0dn.1 9287us : free_hot_cold_page (free_hot_page)
ldconfig-26779 0dn.2 9287us : __mod_page_state_offset
(free_hot_cold_page)
ldconfig-26779 0dn.1 9288us : preempt_schedule (free_hot_cold_page)
ldconfig-26779 0dn.1 9289us : mod_page_state_offset (free_pgd_range)
ldconfig-26779 0dn.1 9290us : free_page_and_swap_cache (free_pgd_range)
ldconfig-26779 0dn.1 9291us : put_page (free_page_and_swap_cache)
ldconfig-26779 0dn.1 9291us : __page_cache_release (put_page)
ldconfig-26779 0dn.1 9292us : preempt_schedule (__page_cache_release)
ldconfig-26779 0dn.1 9293us : free_hot_page (__page_cache_release)
ldconfig-26779 0dn.1 9293us : free_hot_cold_page (free_hot_page)
ldconfig-26779 0dn.2 9294us : __mod_page_state_offset
(free_hot_cold_page)
ldconfig-26779 0dn.1 9295us : preempt_schedule (free_hot_cold_page)
ldconfig-26779 0dn.1 9295us : mod_page_state_offset (free_pgd_range)
ldconfig-26779 0dn.. 9297us : preempt_schedule (unmap_region)
ldconfig-26779 0dn.. 9298us : schedule (preempt_schedule)
ldconfig-26779 0dn.. 9298us : profile_hit (schedule)
ldconfig-26779 0dn.1 9299us+: sched_clock (schedule)
<...>-26580 0d..2 9306us+: __switch_to (schedule)
<...>-26580 0d..2 9309us : schedule <ldconfig-26779> (76 13)
<...>-26580 0d..1 9310us : trace_stop_sched_switched (schedule)
<...>-26580 0d..2 9310us : trace_stop_sched_switched <<...>-26580>
(13 0)
<...>-26580 0d..2 9312us : schedule (schedule)
Lee
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