From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4667D2CC.2060006@domain.hid> Date: Thu, 07 Jun 2007 11:41:32 +0200 From: Jan Kiszka MIME-Version: 1.0 References: <7289437c0706060801i299d6881w31cc5ffee3444ace@domain.hid> <1181143109.17978.101.camel@domain.hid> <7289437c0706062254v2a386894oeb498459877d5086@domain.hid> <4667AA4D.6070505@domain.hid> <7289437c0706070042gf4346ddj1c4ee3ac20a068d2@domain.hid> <4667BBBE.1040405@domain.hid> <4667CEF2.2050509@domain.hid> <4667D008.80109@domain.hid> <4667D167.9030001@domain.hid> In-Reply-To: <4667D167.9030001@domain.hid> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig390DEBB0F84618DE8D721C82" Sender: jan.kiszka@domain.hid Subject: Re: [Xenomai-help] Cyclictest List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gilles Chanteperdrix Cc: xenomai-help This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig390DEBB0F84618DE8D721C82 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Gilles Chanteperdrix wrote: > Jan Kiszka wrote: >> Gilles Chanteperdrix wrote: >> >>> Jan Kiszka wrote: >>> >>>> Perrine Martignoni wrote: >>>> >>>> >>>>> Ok. I'll do this. >>>>> >>>>> But I don't understand why the same application compiled without an= y links >>>>> with Xenomai give different results if there is Xenomai in the kern= el. >>>> [Looking at your numbers again] Hmm, maybe some rounding issue of ti= cks >>>> due to whatever side-effect of I-pipe. We would first of all need th= e >>>> usual set of information (.config, involved versions) and also >>>> /sys/devices/system/clocksource/clocksource0/current_clocksource. >>> Maybe what Perrine is observing is simply the overhead of the I-pipe = ? >>> I mean, Linux is Xenomai idle task, so it is acceptable for Linux >>> numbers to be a bit worse than when Xenomai is not running. >> >> I bit worse is expected. But I think we are seeing 1 or 2 ticks wake-u= p >> delays here. As far as I understood, they are not due to Xenomai >> consuming significant cycles in the background, are they, Perrine? >=20 > What I see is latencies 5us longer. 5us on ARM is almost nothing, keep > in mind that a simple syscall on ARM already takes 10 us. >=20 T: 0 ( 732) P:99 I: 10500 C: 2291 Min: 41 Act: 2281 Avg: = 5075 Max: 10224=20 vs. T: 0 ( 893) P:99 I: 10000 C: 1756 Min: 13407 Act: 13536 Avg: = 13452 Max: 13693=20 Thus the _minimum_ and the _average_ wakeup time of a Linux task increase fairly significant here. That's the point. Given a reasonable runtime of both test, this /could/ be considered as a regression of a Xenomai-enabled Linux kernel. Jan --------------enig390DEBB0F84618DE8D721C82 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFGZ9LMniDOoMHTA+kRAjDIAJ9F+NEPWZAG7z0SsjLhUmxWNdMPJwCfcV1M 2XWpKMSVkdZTGaajvscvlRE= =jjut -----END PGP SIGNATURE----- --------------enig390DEBB0F84618DE8D721C82--