From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4458625C.5020808@domain.hid> Date: Wed, 03 May 2006 09:57:16 +0200 From: Jan Kiszka MIME-Version: 1.0 Subject: Re: [Xenomai-help] Have condition variables Priority Inheritance Protection (PIP)? References: <200604281736.28169.lbocseg@domain.hid> <44527E39.7090501@domain.hid> <200605020936.00576.lbocseg@domain.hid> In-Reply-To: <200605020936.00576.lbocseg@domain.hid> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig6D03A4966B5369F910C0AB16" 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: Rodrigo Rosenfeld Rosas Cc: xenomai@xenomai.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig6D03A4966B5369F910C0AB16 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: quoted-printable Rodrigo Rosenfeld Rosas wrote: > Em Sexta 28 Abril 2006 17:42, Jan Kiszka escreveu: >=20 >> ... >>> Could someone please point me the reason? >> Just as with semaphores: there is no ownership concept for condition >> variables. Thus, who should be boosted to your priority in case you >> decide to wait on such a resource? >=20 > Sorry, you are right. Xenomai has no way of knowing which tasks could s= ignal=20 > the condition variable. If I wanted to wait on some resource using prio= rity=20 > inheritance I guess I would have to raise the priority of the task owni= ng the=20 > resource manually when only one task can signal the condition variable = (or=20 > semaphore). Do you know other better approaches? I mean if a task A of = > priority 50, shares a resource with task B and C, both priority 10 thro= ugh=20 > semaphores. Suppose B and C are using the semaphore when A requests it.= How=20 > could they be boosted to A's priority, so that A is protected with prio= rity=20 > inheritance and then go back to their original priorities? Or should I = use=20 > other IPC mechanism for sharing resource with PIP? Mutexes were invented for such resource access control :). They have a strict ownership concept, thus allowing to apply PIP as well. Jan --------------enig6D03A4966B5369F910C0AB16 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFEWGJcniDOoMHTA+kRAn8VAJ9TbPQ31zf7ZGnhzTIhLKUDXprUsQCeMSyc YI/9npcSJGW5WHpruhV9nF8= =f1Ie -----END PGP SIGNATURE----- --------------enig6D03A4966B5369F910C0AB16--