-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Ralf Mardorf wrote: > Pardon Rui :) > > Gustin and I are clueless because of HPET. Do you know any link? Or is
I know what an HPET is, I would to know what you mean by "HR Timer" and "System timer". A good primer on what an HPET is, what hardware and OSs support it, can be found on wikipedia:http://en.wikipedia.org/wiki/High_Precision_Event_Timer > there an understandable answer because of the hpet_max_user_freq issue? I have no idea what this does. <snip> > > Gustin Johnson wrote: >> -----BEGIN PGP SIGNED MESSAGE----- >> Hash: SHA1 >> >> Ralf Mardorf wrote: >> >>>>> I do know that MIDI jitter by Linux to equipment external the >>>>> computer will decrease when using HR timer instead of System timer. >>>>> I don't know the impact of the value for hpet_max_user_freq. >>>>> >>>> What is the difference? >>>> >>> http://www.mail-archive.com/[email protected]/msg01458.html >>> >>> >>> >> To be more specific, define for me "System Timer" and "High Performance >> Event Timer" (HPET) and how they are different. >> >> Interestingly Windows XP does not support HPET even if the hardware is >> equipped with it. >> > > AFAIK the system timer is using RTC and it's a programmable timer that > interrupts the hardware periodically, while HPET won't interrupt the > hardware in such a static way, because of the much higher resolution > there will be less conflicts because of interrupts, dunno how this > works. I guess to google for "tickless timer" might give some answers: > > http://www.google.de/#hl=de&ei=bJo2S7L5NdH5_Aar05iMCQ&sa=X&oi=spell&resnum=0&ct=result&cd=1&ved=0CBoQBSgA&q=tickless+timer&spell=1&fp=6e1a413bb204dd20 > > > I didn't read the first link, but this one seems to be interesting and I > guess I'll read it some day: > > http://kerneltrap.org/node/6750 > > Dunno if it's set up for my XP, but I once read a howto enable it for > XP. It was just one short line to add somewhere. I guess you need > service package 3. > > I searched, but I didn't found the link: > > http://www.google.de/#hl=de&q=HPET+XP+sp3&meta=&aq=f&oq=HPET+XP+sp3&fp=6e1a413bb204dd20 > > > There's a discussion about this issue: > > http://forum.slysoft.com/archive/index.php/t-22236.html > > Somewhere is a thread or Wiki about HPET on different OSs and IIRC there > is described how to enable it for XP. But if it should be enabled, it's > unclear if ASIO will use it. > >>> I can't remember if I used 64 or 1024 for hpet_max_user_freq, but >>> IIRC on LAD there was the advice to build the kernel with using 64 by >>> default, even if I should have used 1024, 64 might be the better value. >>> >> >> That does not seem like good advice if we are talking about the same >> thing. >> > > A shot in the dark: The frequency always is 1,000,000,000 Hz for HPET > timers, while the maximal frequency for system timers is 1,000 Hz. It > might be that hpet_max_user_freq is a value how precise an interrupt has > to be forced. If I guess correctly ;), HR timers don't force it when > there are no interrupts needed, while a normal timer always does this > periodically. I can imagine that a value of 64 does mean, that there are > some kind of ticks for the tickless system ;), e.g. ... this might be > complete nonsense ... 1,000,000,000/64=15625000, while > 1,000,000,000/1024=976562.5 ... thus the higher value, will cause a less > precise resolution for sync. I also have a theory the other way around > ;). We should ask this on LAD, instead of puzzling over this issue. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAks27m8ACgkQwRXgH3rKGfNtMwCgnKiKWLzaVd3Pt/3zdalAuRqB kGoAnRiStcUWz8jNKo47CjOcbSagA+nW =wZA8 -----END PGP SIGNATURE----- _______________________________________________ 64studio-users mailing list [email protected] http://lists.64studio.com/mailman/listinfo/64studio-users
