So, At home I had been getting some odd latency with my cd/dvd drive (using jack and alsaplayer, the sound would cut out for a split second, but with no xruns, so I'm thinking it was the drive or the ide channel, and not jack-related). I have an nforce2-based motherboard, with a seagate SATA drive (nforce2 puts SATA on the primary master ide channel), another seagate ide drive, and a pioneer cd/dvd drive. I keep all my soundfiles on the SATA drive (since it's supposed to be faster), and the linux system on the ide drive. My previous setup gave the SATA drive the entire primary channel, put the system drive as secondary master and dvd as secondary slave. I decided to try putting the system drive on the primary channel as slave, and giving the entire secondary channel to the dvd drive as master (this is a setup I have used successfully with other motherboards). So - sound drive is hda, system drive is hdb, and dvd is hdc. Here's the problem-- where I had been getting about 33-35MB/sec on both drives with the previous setup with hdparm -t, when I set it up like this, they both go down to about 6.5MB/sec. This is because dma has been disabled - when I enable it on hdb (hdparm -d1 /dev/hdb) the benchmark runs back up to around 35. On hda, I can enable dma with no errors: # hdparm -d1 /dev/hda /dev/hda: setting using_dma to 1 (on) using_dma = 1 (on) but when I run the benchmark it's still around 6.5MB/sec, and then I notice that dma has again been disabled on BOTH hda and hdb. Anybody know what the hell is going on here? My guess is that the SATA-ide driver won't allow dma (or the default udma mode is wrong or something), and when the SATA drive gets its own ide channel, there's no problem - it's only when it's combined with other drives that there's a problem (it does the same when the cdrom is placed on primary/slave). I'm getting fewer cutouts from the dvd drive (secondary master by itself) when I play a cd, but I'm still getting a few now and then - is there a way to optimize something here so I don't get them? Thanks, Matt
