From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <44E46EDC.1000707@domain.hid> Date: Thu, 17 Aug 2006 15:27:56 +0200 From: Jan Kiszka MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigC82744B0D12B17D4CA51B513" Sender: jan.kiszka@domain.hid Subject: [Xenomai-core] Towards periodic mode over aperiodic timers List-Id: "Xenomai life and development \(bug reports, patches, discussions\)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: xenomai-core This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigC82744B0D12B17D4CA51B513 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: quoted-printable Hi, the conflict between skins preferring aperiodic timing vs. skin requiring periodic mode popped up once again on xenomai-help. One way out of this, likely THE way, is to map such tick-driven skins on a periodic timer over aperiodic mode (and drop periodic low-level support completely at the same time). Let's start some discussion how this can be done, specifically as Gilles and I are already turning the xntimer subsystem upside down (almost). If we want co-existence of high-res timing of, say, the posix skin while the vxworks skin runs over a tick-timer, we need some kind of "context" for timing related functions. Simple example: xnpod_suspend_thread() expects a timeout as "xnticks", i.e. either in nanoseconds or in ticks of the underlying periodic timer. This depends on the global timer mode of the pod, and that's a no-go for concurrent modes as sketched above. Rather, the thread should encode which kind of timing mode to use, even better the threads timers. We currently dispatch xntimer_start globally to the different timer subsystems (if periodic mode is enabled). What about deriving the start function from the timer itself in the future? If a timer was created as aperiodic, things happen as usual in aperiodic mode, and the timeout are interpreted as nanoseconds. If the timer is periodic, we interpret the timeout in ticks and map them on a second-level timing subsystem (probably a wheel) that itself is driven by a single periodic timer in the first-level system (just like the host tick). Am I heading in the right direction? Is it feasible? Any other ideas? Jan --------------enigC82744B0D12B17D4CA51B513 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 iD8DBQFE5G7cniDOoMHTA+kRAsW2AJ4yy+Nkx+TMx7sCkhJTxWPq1FzLPACfdaXa J6vZlSsawoyjCN1L+YGCrOM= =swVv -----END PGP SIGNATURE----- --------------enigC82744B0D12B17D4CA51B513--