From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4B3A30AA.5040103@domain.hid> Date: Tue, 29 Dec 2009 17:39:06 +0100 From: Gilles Chanteperdrix MIME-Version: 1.0 References: <4B3A12B8.9030902@domain.hid> <4B379DFC.6000800@domain.hid> <27218735.319731261932640576.JavaMail.coremail@domain.hid> <27741962.171501262064832984.JavaMail.coremail@domain.hid> <32053907.426821262104373569.JavaMail.coremail@domain.hid> In-Reply-To: <32053907.426821262104373569.JavaMail.coremail@domain.hid> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Xenomai-help] test result on at91rm9200 List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: robert165 Cc: xenomai-help robert165 wrote: >=20 >=20 >=20 > =E5=9C=A82009-12-29=EF=BC=8C"Gilles Chanteperdrix" =E5=86=99=E9=81=93=EF=BC=9A >>robert165 wrote: >>>=20 >>>=20 >>>=20 >>> =E5=9C=A82009-12-28=EF=BC=8C"Gilles Chanteperdrix" =E5=86=99=E9=81=93=EF=BC=9A >>>>robert165 wrote: >>>>> Hi, >>>>> I have tested xenomai on my at91rm9200 board, I used >>>>> xenomai 2.4.10 + linux-2.6.28 + adeos-ipipe-2.6.28-arm-1.12-05.patc= h >>>>> Test result seems very poor, is that correct? >>>> >>>>Your test results are rather good for an at91rm9200 board, which is t= he >>>>sure sign that you are not loading the system enough. >>>> >>>>As I already told, you, the expected results are: >>>>- user-space latency of 260us without FCSE >>>>- user-space latency of 200us with FCSE >>>>- kernel-space latency of 50us if running with unlocked context switc= hes >>>>(an option which is only available in the upcoming 2.5 branch). >>>> >>>>> And is there any introduction of the tests, as their purper, their >>>>> meanling... >>>> >>>>The latency test computes some latencies (either user-space schedulin= g >>>>latency, kernel-space scheduling latency, or kernel-space interrupt >>>>latency, depending on the options). The switchtest tests context >>>>switches. The switchbench measures context switching time. cyclictest= >>>>does the same thing as the latency test (only, you need to run it wit= h >>>>the right options to avoid running in fact with Linux timer), and in >>>>general return similar results. Here I do not know what is the meanin= g >>>>of cyclictest results you got, but if you want to know, I am afraid y= ou >>>>wil have to investigate, or simply ignore them. >>>> >>>=20 >>> Thanks for your introdution, and is there any document of it.=20 >>> The man pages just explain parametres of test scripts. I could >>> not understand the output of some test. >> >>No there is no document. But patches are welcome, as usual. As far as I= >>can tell, I explained you what the tests do, there is not much more to >>tell. Which test's output did you not understand? >> >=20 > when running: ./run -- -p 1000 -T 180 -t2 # latency > result gave negative numbers like=20 > RTH|-----lat min|-----lat avg|-----lat max|-overrun|----lat best|---lat= worst > RTD| -3.739| 11.330| 39.530| 0| -3.739| = 39.530 > Is that means timer interrupts are not perfect, and may occur before or= after the exact moment. > If so, the avg should calculate by the absolute value of the latency, a= nd the best should be=20 > the least absolute value. It is a matter of point of view. From our point of view, the timer interrupt ticking in advance is a feature, it compensates a bit for the latency. Anyway, if you do not like it, just echo 0 > /proc/xenomai/latency The timer interrupts happen at the time they are programmed, only it is their handling which may be delayed, most probably due to interrupts masking sections. --=20 Gilles.