On 10/13/2010 10:20 AM, Michal Sojka wrote:
> On Tue, 12 Oct 2010, Wolfgang Grandegger wrote:
>> Yes, packet losses can also happen, when the message buffers are not
>> read out fast enough. But then you should see overrun errors, which you
>> should see with "candump any,0:0,#FFFFFFFF". See also:
>>
>> http://lxr.linux.no/#linux+v2.6.35.7/drivers/net/can/mscan/mscan.c#L353
> 
> Right.

It's still unclear to me what errors you get? RX overrun errors in
hardware or software? candump is able to detect and report both.

>> Also "# ip -d -s link show can0" should list them.
>>
>>> We were able to avoid losing messages by reading them in hard-irq
>>> context (with lincan driver), but I'm not sure whether this will help if
>>> you use CF (we do not use it).
>>
>> Well, if the CF card driver is causing huge latencies, it should be
>> fixed. It should not be too difficult to spot the latency evil with ftrace.
> 
> I've heard that one company that experienced these problems tried to
> solve it with Thomas Gleixner and he said that it is impossible to fix.
> But that's only what I've heard, I do not know any details.

Hey, it's software! Everything is possible ;-). Feel free to add Thomas
to CC to get more information.

Wolfgang.
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