On 20/02/2018 05:05, Johnny B Good wrote:
On Mon, 19 Feb 2018 10:08:25 +0000, Chris Bartram wrote:

====snip====


Digital audio ripping is very variable according to disk quality and
drive ability, and i've found that reading one dodgy disk can then slow
down subsequent rips until after a reboot.

That sounds like a Microsoft Windows experience.

Actually, recently on Linux. One CD, seemingly undamaged, just refused
to rip, sticking at one point, and then the next one was slow. I was
wondering if the first one was one of those deliberately nobbled ones
from the early 2000s.


The cause was due to
the driver code detecting a high error rate, causing it to drop back to a
lower UDMA performance mode, one stage at a time in the hope of easing
the stress on the interface to eliminate the high rate of errors until
finally resorting to the least stressful[1] of all modes, PIO mode, which
once selected, could not be reverted back to UDMA mode automatically.

If the driver had dropped from UDMA mode 3 down to 2 then 1 before
eliminating the high rate of errors, it could automatically revert back
to the faster UDMA modes provided it hadn't resorted to PIO mode. The
idea behind this behaviour was to automatically select the fastest
reliable UDMA setting with hard disk drives since not all drives fully or
reliably met their claimed UDMA specification.


I've seen all that in the past, but in this case it feels like drive
firmware setting a read rate. That's just a guess, obviously, without
delving very deep. From what I recall, PIO dropback on Windows with an
optical drive survived a reboot?

[snip]