From: Flemming B. <li...@bj...> - 2007-08-23 09:03:39
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My rosegarden, ardour, jack, etc. works fine without problems. Except that, though audacity and xmms should work with jack, they apparently don't (really). I have no xruns. Latency 1.5 or 3 ms. Jack could be more stable, but it is stable when it works with programs that seem to have the jack-plugin implemented well, e.g. rosegarden. However, the realtime kernel may give windows-like problems: sometimes firefox has frozen my system (without realtime kernel this is a very, very rare thing). But, it seems that the memory-swap trick mentioned in the jack README file in jack's source code has helped. I haven't had the problem since I used it. Also, problems with rosegarden stopping under recording have disappeared. Alltogether, my conclusion is that realtime linux and sound work very well and give high quality recording. I made my system work in the following way: First, I use (k)ubuntu. When you use gentoo, you put the more burdens of making things working on yourself. On ubuntu, they use a cunning guy's (Ingo) solution to make a functional realtime kernel: There is a fine realtime kernel available: https://wiki.ubuntu.com/RealTime/Feisty You can also compile this kernel yourself, but you need to patch the kernel with Ingo's patch, and you don't use the newest kernel but wait untill Ingo has updated the patch (unless you choose to help Ingo). You can easily find more details on the net. Incidentally, I have with success followed: http://tapas.affenbande.org/wordpress/?page_id=40 Second, I have had severe problems with hardware: maudio 2496 + asus motherboards is a bad cocktail. It took a long time to realise that I had hardware problems! Flemming søn, 19 08 2007 kl. 14:52 -0400, skrev Richard Cooper: > I gave up trying to get sound out of music some time ago. Desite finally > recieving a emu10k from a friend, which helped somewhat, Linux seemed to > become worse at multitasking with ever new kernel version, rendering > ZynAddSubFX entirely useless, Jack unable to avoid miles of xruns despite > using the largest period size qjackctl allows, and even my MP3 player > couldn't play audio correctly without realtime priority. I even > downloaded a program called "bfr" which also contains a "bfp" which > buffers data recieved on standard input, then plays it through the audio > device. Despite the fact that at any time it had 30 seconds of audio data > available to immediately send to the audio device just as soon as it > indicated that it wanted more, it also couldn't play audio without > constant dropouts either, unless I ran it with realtime priority. > > Realizing that a hard disk was failing (thanks smartctl) I reinstalled my > Gentoo system, and in doing so I upgraded to kernel 2.6.21. I noticed a > new option, "tickless timer," and immediately remembered bitching several > years ago on a mailing list or in a newsgroup somewhere about how the > whole HZ=anything stuff sucks because it's just as easy to schedual > interrupts for exactly the moment you want them. I don't recall ever > convincing anyone it was a good idea or even possible, but it's nice to > see it finally happening, even if it doesn't appear to work at the moment > as I'm still getting 1000 interrupts a second on an idle system. Anyway, > this prompted me to try the musical side of Linux again. > > After spending some eight hours trying to figure out why I couldn't build > the realtime-lsm module, then trying the rlimit method of assigning > realtime privledges only to learn that my kernel seems to have no idea > that realtime priority exists, and then remembering that I never bumped > into the option for it in "make menuconfig" and then looking for it and > being completely unable to find it, I decided to just give things a try > anyway, even without realtime priority. > > I was absolutely amazed. Even *without* realtime priority, I could > compile programs while using Jack and still have hardly any xruns. I > don't think it was a result of the "tickless timer" but I suppose it might > have been. Whatever the reason, it was absolutely fucking amazing how > much better this kernel works. > > ...but, I say "was" because now that a new day has come, it no longer > works. > > I haven't a clue what happened. It now seems the kernel does know what > realtime priority is, and it also now seems that Jack refuses to start up > if its request for realtime priority fails, and disabling its request for > realtine priority results in an endless stream of xruns even on an idle > system. > > I don't have a clue how it was all working yesterday. I never had any > means for my user to use realtime priority as I still cannot figure out > how to build a "realtime" kernel module and the PAM system keeps saying > "unknown limit item 'rtprio'" so I'm not getting realtime privledges from > that either. There doesn't seem to be any means by which Jack could have > aquired realtime privledges even if I am mistaken in my belief that > qjackctl clearly indicated it was running without realtime priority. > ...and I know I never unchecked that "realtime priority" box in qjackctl > either. I vaguely remember a "no" after "Realtime Priority" in the status > box, and a dark yellow "RT" in the main status window, which indicated to > me that realtime priority wasn't working since it wasn't bright yellow, > although I notice now that disabling realtime priority causes that to > appear as a simple hyphen instead so maybe I'm just mistaken about it all. > > Anyway, I'd be so happy if someone can guess what might have happened > yesterday to make it all work so well. My best guess is that it was just > a very, very lucid dream, but I've never known myself to become that > confused as to the difference between dreams and reality, so it's still > possible it really happened. > > I also cannot figure out what in menuconfig I am supposed to answer "m" to > to create the "realtime" module that I "modprobe realtime gid=100" to in > order to give realtime priortity to users. My best guess is that the > option no longer exists anymore, but I've had such a hard time finding > things in menuconfig before that the fact that I've went over everything > twenty times doesn't convince me that the option isn't still in there > somewhere, just difficult to find. I notice there's no longer any mention > of "SELINUX" in the .config file, so maybe it is just gone. I suppose one > other possibility is that "emerge realtime-lsm" in Gentoo fails to > correctly install the patch. > > I've since installed 2.6.22 hoping I'd have better luck with it, but > everything is the same. > > I just don't know what to make of it all. > > ------------------------------------------------------------------------- > This SF.net email is sponsored by: Splunk Inc. > Still grepping through log files to find problems? 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