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

rwhron@earthlink.net
Mon, 13 Jan 2003 21:49:49 -0500


>> 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

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