From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <44900A19.1040702@domain.hid> Date: Wed, 14 Jun 2006 15:07:37 +0200 From: Jan Kiszka MIME-Version: 1.0 Subject: Re: [Xenomai-core] ns vs. tsc as internal timer base References: <448E98A3.6080707@domain.hid> <448E9E8B.70809@domain.hid> <448EA7F7.5000802@domain.hid> <448EB038.8070802@domain.hid> <448EE593.7010809@domain.hid> <448EF022.1040901@domain.hid> <17550.61982.685449.470866@domain.hid> <448EFCC5.60308@domain.hid> <448FD5EC.4060109@domain.hid> <44900143.50806@domain.hid> In-Reply-To: <44900143.50806@domain.hid> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigD8FFE2A0E19C20E554BD905F" 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-core This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigD8FFE2A0E19C20E554BD905F Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: quoted-printable Philippe Gerum wrote: > Jim Cromie wrote: >> Philippe Gerum wrote: >> >>> Gilles Chanteperdrix wrote: >>> >>>> Philippe Gerum wrote: >>>> > Redone the check here on a Centrino 1.6Mhz, and still have >>>> roughly x20 > improvement (a bit better actually). I'm using >>>> Debian/sarge gcc 3.3.5. >>>> >>>> I think I remember that Pentium M has a much shorter mull instructio= n >>>> than other processors of the family. >>>> >>> >>> That would explain. Anyway, as John Stulz put it: >>> "math is hard, lets go shopping!" >>> >> >> Heh. Appropriate that his name (Stultz) comes up here, as his >> generic-time (GTOD) >> patchset looks headed for 2.6.18, bringing with it a full re-working >> of linux timers / timeofday. IN this new world, time is kept on >> free-running counters. >> >> Ive been running this patchset on my soekris for some time, since >> GTOD detects that the TSC counts slowly, calls it insane, and does tim= ing >> with the PIT. >> >> With GTOD, writing a new clocksource driver is easy, enough so I could= >> do it. >> My clocksource patch uses the 27 mhz timer on the Geode CPU. >> Once the TSC is de-rated, mine becomes the best clocksource, and GTOD >> switches to it. >> >> All of which is to say .. >> new mainline code is coming, should this current rework notion wait, >> given that its will all need revisited again later >> >=20 > Clearly yes, since this is going to impact Adeos too. GTOD is going to > fiddle with the PIT channels in a way Adeos needs to be aware of, in > order for the client RTOS to reuse such timer. Added to the flow of > other core changes planned for 2.6.18, this is likely going to be funky= =2E >=20 > "Find wall. Beat head against same." >=20 May not be required: the GTOD and clocksource abstractions could provide a clean way to register some virtual, Adeos- or RTOS-provided clock with Linux. And that clock may even lose ticks without Linux losing its system time! So far for the theory, practice may still require walls... Jan --------------enigD8FFE2A0E19C20E554BD905F 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 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFEkAodniDOoMHTA+kRAgHMAJ9+1GN/pn+zWIPEIZYP6PgGTjnOTwCfcO2I mQZuqAIzEeqlkbXHlWVPAkQ= =ynjz -----END PGP SIGNATURE----- --------------enigD8FFE2A0E19C20E554BD905F--