From: Paul <paul@crubille.lautre.net>
To: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
Cc: xenomai@xenomai.org
Subject: Re: [Xenomai] Linux port to ARM Allwinner A13
Date: Mon, 11 Mar 2013 23:47:37 +0100 [thread overview]
Message-ID: <513E5F09.30600@crubille.lautre.net> (raw)
In-Reply-To: <513D8C24.4010009@xenomai.org>
Some precision and 2 small examples about a preempt test:
On 11/03/2013 08:47, Gilles Chanteperdrix wrote:
> On 03/11/2013 10:15 AM, Paul wrote:
>
>> Hello,
>>
>> ... ... ...
>>
>> I check the priority masking with a preempt test which is derived
>> from the latency test: The real time task loop for 1/4 of its period
>> reading and rereading the clock, so i get the min, avg and worst case
>> that the task can be preempted while it is running.
>
>> If you are interested in this test, i can post it when I have
>> modified the output messages.
>
>
> I do not really understand. Why would it be more preempted in the first
> 1/4 of its period?
>
>
No reason sure but -
It can be preempted only while it is running, so between the time it
is restarted after sleeping and before it go to sleep again.
Let it running 1/4 of the period is enough to catch lots of events if
there is lots of irqs but not too much so linux, dohell or even xenomai
tasks can run just a bit slower.
Here are some result i get (yes with the priority interrupt masking, and
i am pretty sure it work - but the watchdog is on).
There is a dohell at the same time in the whole experiment and i start
X11, stop it , restart it ...
root@debian:/usr/xenomai/bin#
/usr/src/build_xenomai/src/testsuite/preempt/preempt -p 111
== Sampling period: 111 us
== Test mode: periodic user-mode task
== All results in microseconds
warming up...
RTT| 00:00:01 (periodic user-mode task, 111 us period, priority 99)
RTH|----pre min|----pre avg|----pre max|-overrun|---msw|---pre
best|--pre worst
RTD| 0.333| 0.374| 3.333| 0| 0|
0.333| 3.333
RTD| 0.333| 0.374| 15.666| 0| 0| 0.333|
15.666
---|-----------|-----------|-----------|--------|------|-------------------------
RTH|----pre min|----pre avg|----pre max|-overrun|---msw|---pre
best|--pre worst
RTD| 0.333| 0.374| 3.708| 0| 0| 0.333|
23.333
RTD| 0.333| 0.374| 3.874| 0| 0| 0.333|
23.333
RTD| 0.333| 0.374| 3.541| 0| 0| 0.333|
23.333
RTD| 0.333| 0.374| 3.916| 0| 0| 0.333|
23.333
RTD| 0.333| 0.374| 3.541| 0| 0| 0.333|
23.333
RTD| 0.333| 0.374| 3.583| 0| 0| 0.333|
23.333
RTD| 0.333| 0.374| 3.499| 0| 0| 0.333|
23.333
RTD| 0.333| 0.374| 3.833| 0| 0| 0.333|
23.333
RTD| 0.333| 0.374| 3.791| 0| 0| 0.333|
23.333
RTD| 0.333| 0.374| 3.666| 0| 0| 0.333|
23.333
RTD| 0.333| 0.374| 3.833| 0| 0| 0.333|
23.333
RTD| 0.333| 0.374| 3.749| 0| 0| 0.333|
23.333
RTD| 0.333| 0.374| 3.749| 0| 0| 0.333|
23.333
RTD| 0.333| 0.374| 3.624| 0| 0| 0.333|
23.333
^C---|-----------|-----------|-----------|--------|------|-------------------------
RTS| 0.333| 0.374| 23.333| 0| 0|
00:13:33/00:13:33
A second experiment, just setting the period to 100 (and the period for
the watchdog is a multiple so 3/4 it never preempt the task:
/usr/src/build_xenomai/src/testsuite/preempt/preempt -p 100 -h
== Sampling period: 100 us
== Test mode: periodic user-mode task
== All results in microseconds
warming up...
RTT| 00:00:01 (periodic user-mode task, 100 us period, priority 99)
RTH|----lat min|----lat avg|----lat max|-overrun|---msw|---lat
best|--lat worst
RTD| 0.333| 0.374| 0.749| 0| 0|
0.333| 0.749
RTD| 0.333| 0.374| 2.749| 0| 0|
0.333| 2.749
RTD| 0.333| 0.374| 0.708| 0| 0|
0.333| 2.749
RTD| 0.333| 0.374| 0.833| 0| 0|
0.333| 2.749
RTD| 0.333| 0.374| 0.708| 0| 0|
0.333| 2.749
RTD| 0.333| 0.374| 0.833| 0| 0|
0.333| 2.749
... ... ...
RTD| 0.333| 0.374| 3.749| 0| 0|
0.333| 4.541
RTD| 0.333| 0.374| 4.166| 0| 0|
0.333| 4.541
RTD| 0.333| 0.374| 3.541| 0| 0|
0.333| 4.541
RTD| 0.333| 0.374| 3.791| 0| 0|
0.333| 4.541
RTD| 0.333| 0.374| 3.666| 0| 0|
0.333| 4.541
RTD| 0.333| 0.374| 4.416| 0| 0|
0.333| 4.541
RTD| 0.333| 0.374| 3.791| 0| 0|
0.333| 4.541
RTD| 0.333| 0.374| 3.874| 0| 0|
0.333| 4.541
RTD| 0.333| 0.374| 3.749| 0| 0|
0.333| 4.541
RTT| 00:04:13 (periodic user-mode task, 100 us period, priority 99)
RTH|----lat min|----lat avg|----lat max|-overrun|---msw|---lat
best|--lat worst
RTD| 0.333| 0.374| 4.124| 0| 0|
0.333| 4.541
^C---|--param|----range-|--samples
HSD| min| 0 - 1 | 253
---|--param|----range-|--samples
HSD| avg| 0 - 1 | 2530149
---|--param|----range-|--samples
HSD| max| 0 - 1 | 3
HSD| max| 1 - 2 | 1
HSD| max| 2 - 3 | 3
HSD| max| 3 - 4 | 186
HSD| max| 4 - 5 | 60
HSH|--param|--samples-|--average--|---stddev--
HSS| min| 253| 0.000| 0.000
HSS| avg| 2530149| 0.000| 0.000
HSS| max| 253| 3.182| 0.583
---|-----------|-----------|-----------|--------|------|-------------------------
RTS| 0.333| 0.374| 4.541| 0| 0|
00:04:13/00:04:13
next prev parent reply other threads:[~2013-03-11 22:47 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-26 0:11 [Xenomai] Linux port to ARM Allwinner A13 Paul
2013-02-25 22:28 ` Gilles Chanteperdrix
2013-03-11 9:15 ` Paul
2013-03-11 7:47 ` Gilles Chanteperdrix
2013-03-11 8:15 ` Gilles Chanteperdrix
2013-03-11 22:29 ` Paul
2013-04-09 22:05 ` Gilles Chanteperdrix
2013-03-11 22:47 ` Paul [this message]
2013-03-12 4:56 ` Gilles Chanteperdrix
2013-03-12 5:06 ` Gilles Chanteperdrix
-- strict thread matches above, loose matches on Subject: below --
2013-05-06 12:56 kunming yang
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