From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <456EF9F8.6080409@domain.hid> Date: Thu, 30 Nov 2006 16:34:16 +0100 From: Jan Kiszka MIME-Version: 1.0 Subject: Re: [Xenomai-help] measuring context switch primary<->secondary mode References: <456D5075.1060905@domain.hid> <200611301119.01173.schwab@domain.hid> <456EE120.5060003@domain.hid> <456EE4EC.5050305@domain.hid> <456EE9C4.6000203@domain.hid> In-Reply-To: <456EE9C4.6000203@domain.hid> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig30F605258A02D711E8BF51CA" 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: Markus.Franke@domain.hid Cc: xenomai-help This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig30F605258A02D711E8BF51CA Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: quoted-printable Markus Franke wrote: > Jan Kiszka wrote: >> CONFIG_PREEMPT helps here to reduce the worst case (PREEMPT_RT even >> more, but it currently collides with patching the kernel). On the othe= r >> hand, it increases the overhead for your Linux subsystem (check with >> lmbench e.g.). Still, depending on what you need, you are able to tune= >> Linux'es own preemption model freely when using Xenomai and I-pipe. >=20 > So at the moment it is not possible to use PREEMPT_RT-Patch and > Xenomai/Adeos together? [adding the list to CC again] If you browse the Xenomai and I-pipe code, you will find some hints that this once worked and Xenomai is basically prepared for it. To combine both patches today, we would have to adopt I-pipe not only to genirq (which is almost done for 2.6.19), but also to the full hrtimer+dyntick (clocksource/clockevent) infrastructure. Moreover, quite some time has passed since the last I-pipe/-rt combo patch, and both PREEMPT_RT and I-pipe changed since then. Do there might be more subtle issues hidden for a combination. Still, this is technically feasible and will come over the time when PREEMPT_RT continues to "leak" into mainline. The question is if using the result (CONFIG_IPIPE+CONFIG_PREEMPT_RT) is also what you want: Combining both strategies also means adding overhead of I-pipe's paravirtualisations and PREEMPT_RT's IRQ threading & sleeping locks. The future development, Xenomai 3, therefore aims at rebasing the nucleus over the -rt patch while keeping its ability to run alternatively over vanilla + I-pipe. Depending on your requirements - full system preemptibility vs. focused RT-subsystem - you will then be able to switch the model without application or driver rewrites. Jan --------------enig30F605258A02D711E8BF51CA 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 iD8DBQFFbvn4niDOoMHTA+kRAoBhAJ9FMXl4UFfMbQopebZXcgeoDArGIQCfS7HY FB/Vuy2plKaaz3g2tsWEmik= =7bwt -----END PGP SIGNATURE----- --------------enig30F605258A02D711E8BF51CA--