Re: IDE DMA disabled with via82cxxx on kernels >= 2.5.35

[rwhron@earthlink.net]

>> Recent 2.5 kernels boot with "DMA disabled".

> It turns it on again but forgets to tell you. Its on the fix list
> but for 2.4 first

Actual throughput on Athlon is better then hdparm lets on.  A 
dd test on 2.5.53-mm1 shows about 120 MB/sec for a file that fits in 
memory.

# time dd if=/dev/zero of=/tmp/junk bs=4M count=100
100+0 records in
100+0 records out

real    0m3.312s
user    0m0.002s
sys     0m3.267s

# ls -lh /tmp/junk
-rw-r--r--    1 root     root         400M Jan 13 21:43 /tmp/junk

hdparm -tT on the K6/2 shows similar throughput between 2.4 and 2.5.

Maybe my hdparm is just wacky on 2.5.  

2.4.20-pre3-jam1:

/dev/hda:
 Timing buffer-cache reads:   128 MB in  0.70 seconds =182.86 MB/sec
 Timing buffered disk reads:  64 MB in  2.07 seconds = 30.92 MB/sec

2.5.53-mm1

/dev/hda:
 Timing buffer-cache reads:   128 MB in  7.20 seconds = 17.78 MB/sec
 Timing buffered disk reads:  64 MB in 19.66 seconds =  3.26 MB/sec

-- 
Randy Hron
http://home.earthlink.net/~rwhron/kernel/bigbox.html