From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <43B40B58.4070408@domain.hid> Date: Thu, 29 Dec 2005 17:14:16 +0100 From: Jan Kiszka MIME-Version: 1.0 Subject: Re: [Xenomai-core] autostart timer, rt_timer_start/stop References: <43B3EAFA.2050906@domain.hid> <43B3FABA.4050903@domain.hid> <43B40254.601@domain.hid> In-Reply-To: <43B40254.601@domain.hid> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig8D58DD20B2A60125CE937139" Sender: jan.kiszka@domain.hid List-Id: "Xenomai life and development \(bug reports, patches, discussions\)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Philippe Gerum Cc: xenomai@xenomai.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig8D58DD20B2A60125CE937139 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Philippe Gerum wrote: > Jan Kiszka wrote: > >> Stefan Kisdaroczi wrote: >> >>> Hi, >>> >>> cant the timer be started by default ? >>> >>> The current state (2.0.1) seems to lead to the following scenario: >>> 1) Every app calls rt_timer_start() >>> 2) If you call rt_timer_stop you can hurt other rt-apps, so dont >>> call it >>> 3) As some apps dont stop the timer, check in 1) if its already running >>> >>> I think most apps do not care in which mode the timer is running if >>> it is already, >>> and just go on, of course you can stop and restart the timer if its a >>> wrong state, >>> but you do not know if you hurt others. >>> >>> Now, as i read in the other thread that the periodic timer support >>> isnt configured by default, >>> why not start the oneshot timer automatic ? >>> >>> Like this, a 'normal' app doesnt need to fiddle with the timer and >>> an app that really cares can still call rt_timer_inquire,_stop,_start. >>> >> >> >> Yea, that's good that someone else brings this topic up again! :) I've >> been pointing on this several times, but as we did not come to a >> conclusion how to handle the system timer in a consistent way across all >> skins, no one (me included...) came up with a fix of this issue so far. >> > > Looks like pending, indeed: > https://gna.org/bugs/?func=detailitem&item_id=4551 > Ha, totally forgot this one - I actually posted it. :) >> The thing is that most skins start the timer during module init via some >> parameter (nowadays also as a kernel boot option for compiled-in skins). >> As far as I remember, only the native and the RTAI compat skin do their >> own dance - the latter one has to remain compatible, ok, but the former >> one should be allowed to perform smarter. >> >> Ok, to be more concrete: autostarting the one-shot time in the absence >> of periodic mode is certainly worth considering. For the other cases and >> as sysfs is no option on 2.4 kernels, what about adding a /proc-exported >> control mechanism for the timer mode (and period) to either the HAL or >> the nucleus? > > > Nucleus. > > Additionally, we could provide some CONFIG_xyz to set the > >> default mode during compile time. >> > > Since we can't have more than a single timer setting at any time, a > CONFIG switch in the General menu would be ok. In such a case, moving > the currently arch-dep CONFIG_XENO_HW_PERIODIC_TIMER to the General > config section would make sense too, so that we would have all timer > options at the same place (periodic timing can always be emulated using > some underlying oneshot hw timer, and all archs are expected to provide > at least some form of oneshot timer anyway). > >> Ceterum censeo rt_timer_start/stop esse delendam. ;) >> > > Perhaps not, otherwise we would have some trouble crafting tests and > benchmarks for instance. But these are indeed relics from the Stone Age > we'd better deprecate for normal use. > Let's assume we have extended /proc/xenomai/timer by accepting the timer period as input (comparable to tick_hz module paramters of some skins), we could simply tune it at benchmark startup by issuing "echo 0 > /proc/xenomai/timer", either in the start script or from within the application. BTW, would the /proc/xenomai/timer interface make sense to you? Jan --------------enig8D58DD20B2A60125CE937139 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 Thunderbird - http://enigmail.mozdev.org iD8DBQFDtAtYniDOoMHTA+kRAtIyAJ9gbXGfa7WbLL1oz3V89uqPcxCffgCcCYQp 008mWqVqa6esgo5J+Y0aHYo= =ktuE -----END PGP SIGNATURE----- --------------enig8D58DD20B2A60125CE937139--