On 2020年07月06日 13:59, Greg Gallagher wrote:
Hi
On Sun, Jul 5, 2020 at 9:36 PM chensong via Xenomai <[email protected]> wrote:
On 2020年07月03日 17:21, Jan Kiszka wrote:
On 03.07.20 08:37, chensong via Xenomai wrote:
In general, we use cyclictest and latency to evaluate the determinism
of our real
time system. As we know, cyclictest and latency use hrtimer to set up
a timer and
calculate jitter by comparing expected wakeup time and real wakeup time.
Besides that, we can also use GPIO to evaluate more modules in
different scenarios.
In this case, i apply 2 GPIO ports, one is set as output, the other is
interrupt,
at the same time, connect them with a cable. Once an signal is sent
from output pin,
an interrupt will be raised in interrupt pin immediately.
Timestamps are recorded before gpio_set_value and interrupt handler
respectively, the
diff between them is jitter.
There is also an RT task running in the user space, which collects the
information and
output the summary at the end of the test. What's more, it also
records the timestamps
in user space, syscall overhead is included.
Further, Making a little change will enable the tool working with
latency box,once a
signal from latency box is received in interrupt pin, the tool can
send a signal at
output pin as response. (I haven't got the latency box, so this
function is not in
place yet)
chensong (2):
demo/posix/cobalt: App of gpio loopback benchmark
kernel/driver/testing: Driver of gpio loopback benchmark
demo/posix/cobalt/Makefile.am | 6 +
demo/posix/cobalt/gpioloop.c | 516
+++++++++++++++++++++++++++++++++++++
kernel/drivers/testing/Kconfig | 7 +
kernel/drivers/testing/Makefile | 3 +
kernel/drivers/testing/gpiobench.c | 288 +++++++++++++++++++++
5 files changed, 820 insertions(+)
create mode 100644 demo/posix/cobalt/gpioloop.c
create mode 100644 kernel/drivers/testing/gpiobench.c
That is a valuable addition! We used to have such an interrupt benchmark
in Xenomai 2 times or so, using a null modem connection (UART signals).
GPIOs are more generic, though.
Two things I would recommend doing differently:
- use RTDM GPIO device (maybe adding missing RTDM GPIO driver for
your targets)
gpiobench.c in patch2/2 is referring to gpio-core.c in
kernel/driver/gpio, they use similar RTDM strcuts or APIs such as
rtdm_driver, rtdm_dev_register.
Could you please give me a sample of RTDM GPIO device? or what kind of
RTDM GPIO driver did i miss?
You could add a proper RTDM gpio driver similar to
kernel/drivers/gpio/gpio-omap.c
They are pretty easy to add since there's a gpio framework in Xenomai
that uses some functions from gpiolib. This commit
d4416d68082f538cdbf08579f99738adbe80d39c may help as an example on how
to add a new gpio driver. Let me know if I can help.
i think i understand gpio framework in gpio-omap.c and gpio-core.c,
therefore, gpiobench.c in my patch can be replaced. what's more, a new
file like gpio-bcm2711.c is needed.
I also looked into /testsuite/gpiotest/gpiotest.c, it's working with
gpio-core.c and read the timestamp of gpio interrupt, however, there is
no histogram, nor reacting to latency-box. i'm considering to add such
functionalities in either gpiotest.c or still in gpioloop.c of my patch?
which one would you prefer?
by the way, could you please let me know how gpiotest is triggered in
smokey test,i read the code of smokey test and didn't manage to figure
it out.
-Greg
