Re: C_CAN: can frame drops

[Oliver Hartkopp <socketcan@hartkopp.net>]

Hi Sagar,

unfortunately I'm not really a C_CAN expert.

I know from a Beaglebone Black which run's at 99% busload without any issues
on the two integrated D_CAN controllers.

Do you have these problems with a stock 2.6.37.x on your hardware too?

Can you send the dmesg output of the c_can related content?

Regards,
Oliver

On 24.07.2014 09:40, Ssagarr Patil wrote:
>> Hi Oliver,
>>
>> Thanks for your response :-)
>>
>>>
>>> generally dropping CAN frames on driver level is a complete different problem
>>> in opposite to dropping CAN frames on socket receive level.
>>>
>> Agreed.
>>
>>> A drop on the socket layer usually occurs, when the application does not get
>>> enough CPU time to read and process the CAN frames. But drops on CAN driver
>>> layer lead to a possible resource problem on your system.
>>>
>> For the application layer I have used chrt so that it gets higher priority.
>>
>>> Can you tell a bit more about your platform (hardware, CPU, cpu clock, RAM)
>>> and Linux Kernel version?
>>>
>> The Linux version is 2.6.37 where as I have patched this kernel to use the v3.15
>> C_CAN driver(which uses D_CAN) to use.
>>
>> Hardware is DM8148 EVM, ARM clock is @1000Mhz, DDR @533Mhz,
> 
> BTW I also tried it on AM335x with the v3.16-rc5 which supports D_CAN
> the problem is the same.
> 
> Thanks,
> --Sagar
> 
>>
>> Regards,
>> --Sagar
>>
>>> Regards,
>>> Oliver
>>>
>>>
>>> On 23.07.2014 16:48, Ssagarr Patil wrote:
>>>> Hi,
>>>>
>>>> I am using the c_can driver for latest kernel and using the latest canutils to dump to a file.
>>>> My can bus is set at a rate of 1Mb (receiving 7000fps bus load of 80%).
>>>>
>>>> When I use the candump tool to dump can frames I get following message,
>>>>
>>>> 'DROPCOUNT: dropped 2223 CAN frames on 'any' socket (total drops 1629092)'
>>>>
>>>> SO to solve this problem if I use the -r option of candump and tried
>>>> candump any -d -e -r 999999999 -l
>>>>
>>>> If I do this the can frames are dropped in the driver ie I see
>>>> this c_can_handle_lost_msg_obj() function being called frequently in which can frame
>>>> is overwritten.
>>>>
>>>> How to solve this issue any pointers would be helpful.
>>>>
>>>> Thanks,
>>>> --Sagar
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