Messages in this thread |  | | From | Alan Chandler <> | Subject | Re: [preview] Latest AMD & VIA IDE drivers with UDMA100 support | Date | Sat, 20 Jan 2001 23:55:13 +0000 |
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On Sat, 20 Jan 2001 14:57:07 -0800 (PST), Andre Hedrick wrote:
... > >Vojtech, I worry that the dynamic timing that you are calculating could >bite you. Timings are exact especially at modes 3/4/5 the margins go to >an effective zero for varition or wiggle room. The state diagrams from >Quantum that created the Ultra DMA 0,1,2,3,4,5 show how darn tight it >constrained. You need to assume absolutes because the various board >makers screw up the skew tables by the PCB lane traces. >
I am not sure this is just a question of small variations. The hdparm -t differences between these two versions is quite significant. This evidence would imply that the two approaches are making fundemental different decisions about what my hardware can do!
Under 2.2.17
/dev/hda: Timing buffered disk reads: 64 MB in 21.86 seconds = 2.93 MB/sec
/dev/hdc: Timing buffered disk reads: 64 MB in 20.81 seconds = 3.08 MB/sec
Under 2.4.0
/dev/hda: Timing buffered disk reads: 64 MB in 6.58 seconds = 9.73 MB/sec
/dev/hdc: Timing buffered disk reads: 64 MB in 6.59 seconds = 9.71 MB/sec
Alan
alan@chandlerfamily.org.uk http://www.chandler.u-net.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
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