DMA, kernel 2.6.6 and CD/DVD
Is there a known problem with DMA for CD and DVD drives with the 2.6.6
kernel?
On my G3 iBook (600MHz) I am getting very high CPU usage with copying
from a DVD or CD, "cp /dev/hdb /dev/null" results in 100% CPU usage with
about 80% being "iowait". hdparm indicates that DMA is enabled. I also
get very low throughput rates (hdparm -t) especially for writable media
where they are 5-600 kB/sec.
ephiny:~# hdparm -i /dev/hdb
/dev/hdb:
Model=SONY CD-RW CRX800E, FwRev=1.3g, SerialNo=
Config={ Fixed Removeable DTR<=5Mbs DTR>10Mbs nonMagnetic }
RawCHS=0/0/0, TrkSize=0, SectSize=0, ECCbytes=0
BuffType=unknown, BuffSize=0kB, MaxMultSect=0
(maybe): CurCHS=0/0/0, CurSects=0, LBA=yes, LBAsects=0
IORDY=on/off, tPIO={min:180,w/IORDY:120}, tDMA={min:120,rec:120}
PIO modes: pio0 pio1 pio2 pio3 pio4
DMA modes: mdma0 mdma1 *mdma2
AdvancedPM=no
* signifies the current active mode
While copying from DVD a typical summary line from top is:
top - 10:03:27 up 34 min, 1 user, load average: 0.29, 0.18, 0.19
Tasks: 87 total, 1 running, 86 sleeping, 0 stopped, 0 zombie
Cpu(s): 15.5% us, 6.9% sy, 0.0% ni, 0.0% id, 75.7% wa, 2.0% hi,
0.0% si
Mem: 386172k total, 272452k used, 113720k free, 41680k buffers
Swap: 515564k total, 4k used, 515560k free, 129496k cached
The kernel is the current debian 2.6.6-powerpc package.
Any suggestions?
James
--
+------------------------+-------------------------------+---------+
| James Tappin | School of Physics & Astronomy | O__ |
| sjt@star.sr.bham.ac.uk | University of Birmingham | -- \/` |
| Ph: 0121-414-6462. Fax: 0121-414-3722 | |
+--------------------------------------------------------+---------+
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