Hunting mode switches

[Jan Kiszka]

On 31.05.21 18:06, François Legal via Xenomai wrote:
> Hello,
> 
> I'm having trouble hunting mode switches on an arm embedded application.
> 
> When I look at cat /proc/xenomai/sched/stat
> 
> CPU  PID    MSW        CSW        XSC        PF    STAT       %CPU  NAME
>   0  0      0          476986     0          0     00218000   84.5  [ROOT/0]
>   1  0      0          137743     0          0     00218000   99.3  [ROOT/1]
>   1  667    0          137550     0          0     00200042    0.7  [rtnet-stack]
>   0  669    0          2          0          0     00220042    0.0  [rtnet-rtpc]
>   1  901    110        218        203        0     00264044    0.0  APP_Main
>   0  911    1          1216       3524       0     00240046    0.0  ThreadPar
>   0  912    3          56683      3531       0     00240046    0.2  ThreadMessage
>   0  913    309702     470522     2152301    0     00240046    8.9  ThreadExec
>   0  914    7          62         71         0     00240042    0.0  TheadGO
>   0  915    3          647        1190       0     00248046    0.0  ThreadDbg
>   0  916    1          2024       3087       0     00248046    0.0  ThreadCt
>   0  917    1          35801      320489     0     00248046    0.8  ThreadSupInv
>   0  918    1          1231       3596       0     00248046    0.0  ThreadMessage2
>   0  919    1          161554     479305     0     00248042    1.4  ThreadSched
>   0  0      0          247850     0          0     00000000    0.4  [IRQ18: [timer]]
>   1  0      0          15419      0          0     00000000    0.0  [IRQ18: [timer]]
>   0  0      0          137548     0          0     00000000    1.5  [IRQ31: rteth0]
>   1  0      0          0          0          0     00000000    0.0  [IRQ31: rteth0]
>   0  0      0          1          0          0     00000000    0.0  [IRQ118: rteth1-tx]
>   1  0      0          0          0          0     00000000    0.0  [IRQ118: rteth1-tx]
>   0  0      0          0          0          0     00000000    0.0  [IRQ119: rteth1-rx]
>   1  0      0          0          0          0     00000000    0.0  [IRQ119: rteth1-rx]
> 
> But when following the procedure in [1], I get 
> no slacker
> 
> I can however see that Thread 913 seem to switch to secondary more than once out of 2 cycles !
> What am I doing wrong.
> 

CONFIG_XENO_OPT_DEBUG_TRACE_RELAX is on?

Did you also try the in-app instrumentation via SIGDEBUG, maybe
attaching gdb to the process to catch the unwanted cases?

Jan

> Thanks in advance
> 
> François
> 
> [1] : https://source.denx.de/Xenomai/xenomai/-/wikis/Finding_Spurious_Relaxes
> 
> 

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