[Xenomai] Powepc 8360 interrupt timing question

[Makarand Pradhan <makarandpradhan@ruggedcom.com>]

  Hi All,

I am doing real time measurements to determine the time required to 
process an interrupt. The interrupt is being handled in  user space. 
rt_intr_wait is used to wait for the interrupt in a xenomai thread. The 
system is a powepc 8360 running linux 3.0, Xenomai 2.6.

The ipipe trace indicates that it takes roughly 60 micro seconds for the 
user space handler to run, after the occurrence of an interrupt. Without 
tracing it roughly takes somewhere between 30 - 50 micro seconds.

I'm not sure if this time is ok for an 8360 or is it too high? Would 
highly appreciate comments on the timings.

The ipipe trace is given below for reference.

Warm Rgds,
Makarand.

*Occurance of int.*
:|  + func                -120+   1.560  ipic_get_irq+0x8 
(__ipipe_grab_irq+0x34) **
:|  + func                -118+   1.545  irq_linear_revmap+0x8 
(ipic_get_irq+0x64)
:|  + begin   0x00000021  -117    0.893  __ipipe_grab_irq+0x48 
(__ipipe_ret_from_except+0x0)
:|  + func                -116+   1.878  __ipipe_handle_irq+0x8 
(__ipipe_grab_irq+0x54)
:|  + func                -114+   1.712  __ipipe_set_irq_pending+0x8 
(__ipipe_handle_irq+0x150)
:|  + func                -112    0.878  __ipipe_ack_irq+0x8 
(__ipipe_handle_irq+0x178)
:|  + func                -112+   1.242  qe_ic_cascade_low_ipic+0x8 
(__ipipe_ack_irq+0x2c)
:|  + func                -110    0.969  qe_ic_get_low_irq+0x8 
(qe_ic_cascade_low_ipic+0x2c)
:|  + func                -109    0.742  irq_linear_revmap+0x8 
(qe_ic_get_low_irq+0x5c)
:|  + func                -109    0.606  __ipipe_qe_ic_cascade_irq+0x8 
(qe_ic_cascade_low_ipic+0x3c)
:|  + begin   0x0000002b  -108    0.651  __ipipe_qe_ic_cascade_irq+0x2c 
(qe_ic_cascade_low_ipic+0x3c)
:|  + func                -107+   1.015  __ipipe_handle_irq+0x8 
(__ipipe_qe_ic_cascade_irq+0x38)
:|  + func                -106+   1.121  __ipipe_ack_level_irq+0x8 
(__ipipe_handle_irq+0xbc)
:|  + func                -105+   1.045  qe_ic_mask_irq+0x8 
(__ipipe_ack_level_irq+0x40)
:|  + func                -104    0.954  irqd_to_hwirq+0x8 
(qe_ic_mask_irq+0x2c)
:|  + func                -103+   1.878  __ipipe_spin_lock_irqsave+0x8 
(qe_ic_mask_irq+0x40)
:|  # func                -101+   1.909  
__ipipe_spin_unlock_irqrestore+0x8 (qe_ic_mask_irq+0x90)
:|  + func                -100    0.606  __ipipe_dispatch_wired+0x8 
(__ipipe_handle_irq+0xc8)
:|  + func                 -99    0.909  
__ipipe_dispatch_wired_nocheck+0x8 (__ipipe_dispatch_wired+0x48)
:|  # func                 -98+   1.469  xnintr_irq_handler+0x8 
(__ipipe_dispatch_wired_nocheck+0x84)
:|  # func                 -97+   1.469  rt_intr_handler+0x8 
[xeno_native] (xnintr_irq_handler+0x84)
:|  # func                 -95+   1.954  xnsynch_flush+0x8 
(rt_intr_handler+0x48 [xeno_native])
:|  # func                 -93+   2.287  xnpod_resume_thread+0x8 
(xnsynch_flush+0xc0)
:|  # [10455] -<?>-  257   -91+   1.409  xnpod_resume_thread+0x6c 
(xnsynch_flush+0xc0)
:|  # func                 -90    0.727  xnsched_rt_enqueue+0x8 
(xnpod_resume_thread+0xa8)
:|  # func                 -89+   3.439  addmlq+0x8 
(xnsched_rt_enqueue+0x44)
:|  # func                 -86+   1.045  __xnpod_schedule+0x8 
(xnintr_irq_handler+0x1f8)
:|  # [10520] -<?>-   86   -85+   1.015  __xnpod_schedule+0x80 
(xnintr_irq_handler+0x1f8)
:|  # func                 -84    1.000  xnsched_pick_next+0x8 
(__xnpod_schedule+0xdc)
:|  # func                 -83+   1.045  xnsched_rt_requeue+0x8 
(xnsched_pick_next+0xb8)
:|  # func                 -82+   1.636  addmlq+0x8 
(xnsched_rt_requeue+0x44)
:|  # func                 -80+   1.242  xnsched_tp_pick+0x8 
(xnsched_pick_next+0x74)
:|  # func                 -79    0.681  xnsched_sporadic_pick+0x8 
(xnsched_pick_next+0x74)
:|  # func                 -78+   6.666  getmlq+0x8 
(xnsched_sporadic_pick+0x30)
:|  # [10455] -<?>-  257   -71+   1.393  __xnpod_schedule+0x2d8 
(xnpod_suspend_thread+0x29c)
:|  # func                 -70+   8.227  xnarch_save_fpu+0x8 
(__xnpod_schedule+0x328)

*Xeno thread woken up in user space*
:|  # func                 -62    0.469  
__ipipe_restore_pipeline_head+0x8 (__rt_intr_wait+0x12c [xeno_native])
:|  + end     0x80000000   -61+   3.045  
__ipipe_restore_pipeline_head+0x90 (__rt_intr_wait+0x12c [xeno_native])
:|  + begin   0x80000001   -58    0.727  __ipipe_dispatch_event+0x1ec 
(__ipipe_syscall_root+0x6c)
:|  + end     0x80000001   -58    0.787  __ipipe_dispatch_event+0x244 
(__ipipe_syscall_root+0x6c)
:|  + begin   0x80000000   -57    0.666  __ipipe_syscall_root+0xfc 
(DoSyscall+0x20)
:|  + end     0x80000000   -56+   9.681  __ipipe_syscall_root+0x108 
(DoSyscall+0x20)
:   + func                 -47    0.742  __ipipe_syscall_root+0x8 
(DoSyscall+0x20)
:   + func                 -46    0.606  __ipipe_dispatch_event+0x8 
(__ipipe_syscall_root+0x6c)
:|  + begin   0x80000001   -45    0.969  __ipipe_dispatch_event+0x274 
(__ipipe_syscall_root+0x6c)
:|  + end     0x80000001   -45    0.757  __ipipe_dispatch_event+0x1ac 
(__ipipe_syscall_root+0x6c)
:   + func                 -44    0.893  hisyscall_event+0x8 
(__ipipe_dispatch_event+0x1c4)


*The first call in the int handler.*
:   + func                 -43    0.666  __rt_task_set_mode+0x8 
[xeno_native] (hisyscall_event+0x1e4)
:   + func                 -42    0.772  rt_task_set_mode+0x8 
[xeno_native] (__rt_task_set_mode+0x50 [xeno_native])

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