From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <456D9031.30807@domain.hid> Date: Wed, 29 Nov 2006 14:50:41 +0100 From: Jan Kiszka MIME-Version: 1.0 Subject: Re: [Xenomai-help] tool for external jitter measurement References: In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig731AD40408343CEB3546791F" Sender: jan.kiszka@domain.hid List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Syed Amer Gilani Cc: xenomai@xenomai.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig731AD40408343CEB3546791F Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: quoted-printable Syed Amer Gilani wrote: > I wrote with my little Xenomai experience a rtdm kernel module witch > generates an external signal to measure it on an Oscilloscope. The > Result is satisfying. With no other load there is nearly no jitter. > With "dd if=3D/dev/zero of=3D/dev/null" and "ping -f" from an external > machine the jitter is +-15=B5sec. 15 us looks fairly good, maybe too good. You may also want to try the cache calibrator as load (see TROUBLESHOOTING for details). > My Question now is if my approach is OK or is there a better way to > generate the signal with Xenomai which would result in better results. > Maybe by using hardware timer interrupt or something? We have postponed the API definition for RTDM timers until the nucleus timers have been reworked (scheduled for 2.4), but that service would probably give you even better results (no reschedule, pins will be toggled in IRQ context). Check drivers/testing/timerbench.c for a hack to achieve this already. Jan --------------enig731AD40408343CEB3546791F Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFFbZAxniDOoMHTA+kRAvfVAJ4+j48ICBVMFaGo3J/KAJeLQosVQwCfZJc6 tLZskT5RYzCRsn5XrJOUWWo= =+BWY -----END PGP SIGNATURE----- --------------enig731AD40408343CEB3546791F--