Re: [Xenomai-help] RTCAN and tsc

[Sebastian Smolorz <ssm@domain.hid>]

Roland Tollenaar wrote:
> Hi
>
> >> What does this mean? This is as good as it gets?
> >
> > Hm. To be more verbose on what happens between the beginning of
> > rtcan_sja_interrupt and rtcan_rcv please remove the "inline" from the
> > functions rtcan_sja_err_interrupt in the file
> > ksrc/drivers/can/sja1000/rtcan_sja1000.c line 156 and from the function
> > rtcan_sja_rx_interrupt in the same file in line 87. Compile your
> > modules/kernel again and repeat the tracer/latency test.
> >
> > I assume that most of the time is spent in the latter function where
> > several SJA HW regs are read out. A slow access to the regs could be the
> > explanation for the long time the interrupt handler has to spend.
>
> Where are the registers located? On the dongle or are these in the PC?

These are registers located in the SJA1000 CAN controller.

> Just to know whether there might not be a problem with the PEAK device.
> Is there any way you could check what the access times are to
> rtcan_sja_interrupt on your systems when performing the same experiment
> and recieving messages (pref PDO with length 8) over the bus?

Unfortunately, I do not have the opportunity to perform tests with the driver 
ATM.

>
> I am developing on a pretty high-end machine here,

Didn't you speak of 486's in a previous mail?

> in fact every aspect 
> almost as fast as is on the market at the moment so its would surprise
> me if there is a hardware shortcoming if the registers you speak of are
> on the PC.
>
> In the mean time I will try doing as you suggest, I presume you want me
> to send the frozen trace to you again after that.

Exactly.

> Is it worth while removing the virtual driver from the kernel build and
> running over rtcan0.

Turn it off although it is unlikely that it has something to do with the 
problem. But you never know.

> Is there any chance that you have never encountered 
> this problem

I never worked with the virtual device.

-- 
Sebastian