On 2020年07月07日 08:42, chensong via Xenomai wrote:
On 2020年07月07日 00:05, Greg Gallagher wrote:
On Mon, Jul 6, 2020 at 5:29 AM chensong <chens...@tj.kylinos.cn> wrote:
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
<xenomai@xenomai.org> 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.
Is this for the Raspberry pi 4? Does that use the bcm2835 gpio
driver? We already have that driver if that's the case.
For Raspberry pi 4b, same with rpi 4? I'm not sure which one. I found
them both in device tree.
If bcm2835 is the right driver, no more work to do.
i verified bcm2835, it's working perfectly with rt task in my app(patch
1/2), therefore, gpiobench.c(patch2/2) is not necessary.
thanks.
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?
i prefer to add asynchronous event in gpioloop.c, once received a signal
from gpio interrupt, send a signal back via gpio out as reaction.
compared to gpiotest.c, gpioloop.c has histogram and ftrace. what do you
say? If it's ok for you, i will start preparing patch v2.
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
