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 instruction >>>> 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 timing >> 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 >> > > 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. > > "Find wall. Beat head against same." >
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
signature.asc
Description: OpenPGP digital signature
_______________________________________________ Xenomai-core mailing list [email protected] https://mail.gna.org/listinfo/xenomai-core
