Subject: [linux-audio-user] hdparm
From: Matt Barber (brbrofsvl_AT_aol.com)
Date: Tue Sep 07 2004 - 02:11:17 EEST
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
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