Re: [Xenomai-help] Adeos/Xenomai Arm Port

[Jan Kiszka <jan.kiszka@domain.hid>]

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Schlägl Manfred jun. wrote:
> On Tue, 2006-10-17 at 17:39 +0200, Schlägl Manfred jun. wrote:
> 
>> 5. latency
>>
>> For periodic user-mode task i need very high periods > 1000us.
>>
>>
>> Here are the latency-checks with printk's of the ioctls:
>>
>> -sh-3.00# ./run -- -t 1
>> *
>> *
>> * Type ^C to stop this application.
>> *
>> *
>> == Sampling period: 100 us
>> == Test mode: in-kernel periodic task
>> == All results in microseconds
>> [42949519.180000] rt_tmbench_ioctl_rt: request 1076364816 -> ret =
>> -ENOTTY(-25)
>> latency: failed to start in-kernel timer benchmark, code -25
>> [42949523.000000] rt_tmbench_ioctl_nrt: request -1071118831 -> ret =
>> -ENOTTY(-25)
>> ---|------------|------------|------------|--------|-------------------------
>> RTS|-1096532.504|       0.001|      93.252|   93340|
>> 00:00:03/00:00:03
>>
>> -sh-3.00# ./run -- -t 2
>> *
>> *
>> * Type ^C to stop this application.
>> *
>> *
>> == Sampling period: 100 us
>> == Test mode: in-kernel timer handler
>> == All results in microseconds
>> [42949529.090000] rt_tmbench_ioctl_rt: request 1076364816 -> ret =
>> -ENOTTY(-25)
>> latency: failed to start in-kernel timer benchmark, code -25
>> [42949534.680000] rt_tmbench_ioctl_nrt: request -1071118831 -> ret =
>> -ENOTTY(-25)
>> ---|------------|------------|------------|--------|-------------------------
>> RTS|-1093751.320|       0.001|      93.252|   93340|
>> 00:00:04/00:00:04
>>
>>
>> Userspace-codes differ from kernelspace-codes, I think...
> 
> 
> 
> Yes it does!!!
> 
> 
> 
> #define RTTST_RTIOC_TMBENCH_START \
>     _IOW(RTIOC_TYPE_TESTING, 0x10, struct rttst_tmbench_config) 
> 
> two different results in kernel-/user-space
> 
> sizeof(struct rttst_tmbench_config) 
> -> kernel 	32
> -> user		40
> 
> 
> typedef struct rttst_tmbench_config {
>     int                     mode;
>     uint64_t                period;
>     int                     priority;
>     int                     warmup_loops;
>     int                     histogram_size;
>     int                     histogram_bucketsize;
>     int                     freeze_max;
> } rttst_tmbench_config_t;
> 
> sizeof(struct rttst_tmbench_config_t)
> -> kernel	32	(uses packed-structure)
> -> user		40	(uses unpacked-structure)
> 
> sizeof(uint64_t)
> -> kernel	8
> -> user		8
> 
> sizeof(int)
> -> kernel	4
> -> user		4
> 
> 
> Difference has something to do with the internal structure of
> rttst_tmbench_config.
> 
> 
> Solution 1: Force userspace-app and kernel to use packed structure
> --------------
> typedef struct rttst_tmbench_config {
>     int                     mode;
>     uint64_t                period;
>     int                     priority;
>     int                     warmup_loops;
>     int                     histogram_size;
>     int                     histogram_bucketsize;
>     int                     freeze_max;
> } __attribute__((packed)) rttst_tmbench_config_t;
> 
> sizeof(struct rttst_tmbench_config_t)
> -> kernel	32	(uses packed-structure)
> -> user		32	(uses packed-structure)
> 
> Has to be done to all structures! (compiler-flag -fpack-struct)
> 
> Problems: 
>  * problems with libs (see
> http://gcc.gnu.org/ml/gcc-help/2005-01/msg00257.html)
>  * possibly problems with typedef ????
> 
> 
> Solution 2: Force userspace-app and kernel to use unpacked structure
> --------------
> typedef struct rttst_tmbench_config {
>     int                     mode;
>     uint64_t                period;
>     int                     priority;
>     int                     warmup_loops;
>     int                     histogram_size;
>     int                     histogram_bucketsize;
>     int                     freeze_max;
> } __attribute__((unpacked)) rttst_tmbench_config_t;
> 
> 
> Kernel ignores the attribute!
> 
> Theoretically:
> sizeof(struct rttst_tmbench_config_t)
> -> kernel	40	(uses unpacked-structure)
> -> user		40	(uses unpacked-structure)
> 
> Has to be done to all structures! 
> 
> 
> 
> 
> Solution 3:
> --------------
> change kernel-configuration to use unpacked structures by default.
> 

I vote for solution 4:

--- include/rtdm/rttesting.h    (revision 1731)
+++ include/rtdm/rttesting.h    (working copy)
@@ -85,8 +85,8 @@ typedef struct rttst_overall_bench_res {

 typedef struct rttst_tmbench_config {
     int                     mode;
-    nanosecs_rel_t          period;
     int                     priority;
+    nanosecs_rel_t          period;
     int                     warmup_loops;
     int                     histogram_size;
     int                     histogram_bucketsize;

Could you check if this helps?

Thanks,
Jan


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