On Mon, 2004-10-11 at 17:40, Mark Knecht wrote: > Lee Revell wrote: > > On Mon, 2004-10-11 at 16:59, Mark Knecht wrote: > > > >>I was building a new kernel under FC2 this morning trying to make FC2 > >>equal to my Gentoo kernel which is working very well. I made a mistake > >>on this new kernel and forgot to turn on 'APIC contoller for UMP > >>machines'. When the kernel booted I got all sorts of xruns. The IRQ > >>was threaded, so I set it for non-threaded but still got a lot of > >>xruns. (>100 in 10 minutes) > >> > >>I rebuilt the kernel where the only change I made was to enable APIC > >>interrupts and IO-APIC controllers for UMP. The kernel booted and has > >>been running for 30 minutes with no xruns... > >> > >>Just another IRQ datapoint, but that was the only change I made... > >> > > > > > > That is really weird, most people report better results _disabling_ APIC > > on UP. > > > > Lee > > > > > Who knows?!? I just take data. I don't interpret it! ;-) > > Could be specific to this ATI chipset's interrupt controller for all I > know. I built a similar kernel yesterday, also under FC2, but on my > older Via KT266 MB with an Athlon XP (I think...) 1600+. That MB only > supports legacy style interrupts and the kernel worked fine, at least at > -p64/-n2 using an HDSP 9652 sound card. > > I did find two strange things about that setup, both sound card related > I think: > > 1) The HDSP driver would not allow me to even try and set -p <64. Just > told me it wasn't allowed. This may be by design. Possibly the way it > moves DMA data it just doesn't support less than that. > > 2) There are two 'regions' of sample rates with that card > > - 32K, 44.1K & 48K (i.e. - 1x) > - 64K, 88.2K & 96K (i.e. - 2x) > > If I try to change from any 1x sample rate to any 2 x sample rate using > Jack I get a message that it cannot do it. Parameters not defined or not > available IIRC. Same going from 2x to 1x. > > However, if I use hdspconf and manually shift from 44.1K (1x) to say 96K > (2x) hdspconf reports that it changed. I can then use Jack to change > between all 2x rates, but I cannot go back to 1x. To go back to 1x I > have to once again use hdspconf. Sounds like a driver issue to me, but > who knows. (I'm not supposed to interpret!) ;-) Yeah, it sounds like that behavior could just reflect the way the hardware works. You should post that to alsa-user if you suspect a bug, the RME stuff is very well supported as you probably know. If you are being limited by the size of a DMA transfer or your cards constraint on DMA buffer size, on some cards (emu10k1) you can get lower latency by recording more channels. Lee Lee
