From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4BF189BA.6060303@domain.hid> Date: Mon, 17 May 2010 20:23:54 +0200 From: Jan Kiszka MIME-Version: 1.0 References: <2319761F7FA0D1479BA77EC2E0A8E7BCE3D6E7@domain.hid><245373446233674495BCA5CA2FC1EB17378D01593B@RCexchangeSVR1.ruggedcom.local> <4BED2910.6020105@domain.hid> <181804936ABC2349BE503168465576460EBD6239@domain.hid> <4BF17464.5090100@domain.hid> <181804936ABC2349BE503168465576460EBD62C8@domain.hid>, <4BF1794A.6050207@domain.hid> <843773D242212C4882D4EDFFBF665F7F0C9F71BAFF@FW-SBS.fw.local> In-Reply-To: <843773D242212C4882D4EDFFBF665F7F0C9F71BAFF@FW-SBS.fw.local> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig838B6F1216617BB503DB2F9C" Sender: jan.kiszka@domain.hid Subject: Re: [Xenomai-help] Question about getting system time List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Josh Karch Cc: "xenomai@xenomai.org" , "Mauerer, Wolfgang" , Andreas Glatz This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig838B6F1216617BB503DB2F9C Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable [please avoid top posting] Josh Karch wrote: > Jan, =20 >=20 > If no ntp server updates are made to the Linux clock, we have noticed = over a week's period a drift of ten or so seconds difference between the = Linux clock and the Xenomai get time function and often have to reboot ou= r machine to resynchronize the Xenomai and Linux clocks back to less than= a couple seconds difference. I was wondering if you might explain why t= hat might happen? I assume you are talking about an x86 platform: Normally, Linux should run on the TSC clocksource, just like Xenomai does. To ensure that the hardware isn't broken, Linux continuously performs runtime checks. The preemption by Xenomai tasks my fool this check an make Linux switch to a different clocksource. Now you have unsynchronized sources that usually drift. I haven't tried this with Xenomai yet but I could imagine it works just like it does in virtual machines: Pass tsc=3Dreliable on the kernel command line. This disables the runtime checks, thus should take away any reason Linux may want to switch to anything else than TSC. Jan --------------enig838B6F1216617BB503DB2F9C Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org iEYEARECAAYFAkvxib4ACgkQitSsb3rl5xT0gQCfat4HbguDrNLg4cntTn+TVkFY 4EMAoO6fh1KnG3JqOVXGIaL2MypDwwvs =/Oef -----END PGP SIGNATURE----- --------------enig838B6F1216617BB503DB2F9C--