[Paranoia] Parallel ripping causes extreme slowdowns

[grarpamp]

On 12/14/19, Merlijn Wajer <merlijn at wizzup.org> wrote:
> In general, we use Intel NUC
> Linux 5.0.
> PL2773 SATAII bridge controller - USB
> Liteon ODD "iHAS 124"

> the internal USB bus and the thunderbolt3 interface.

Thunderbolt is PCI and DP... separate from USB,
unless using the USB controller part of t3.

> (Tangent: USB2 has a limit of 480Mbit/s if I recall correctly, so that
> should really be no problem for two drives?)

CD 1x is roughly 150kB/s, they would self destruct before then.

> It tries to
> reset and re-read, and while that happens, the other two drives are just
> blocking. As far as I can tell, there should be no reason for that to
> happen, but it suggests that the problem is not cdparanoia (as
> expected), but rather somewhere on the scsi or driver level?

The usb or scsi layer driver could be going through some
form of lock waiting on the drive or hw, that could take
out all consumers of the driver regardless of bus.
Or if all the drives are on the same bus or drive controller,
a reset etc to either of those two hw could freeze everything
downstream of them till it resolves.

> Do you have suggestions for tools and settings to use to investigate the
> possibly activity that you mention?

The debug level you have set could be filtered to make
things more visible for you... there's piles of the same
12 byte commands, probably boring reads.

Search for scsi / ata command set, scsi / sg / sr manpage.

Strace would capture the application sw, but there's
probably some driver specific debug options.

If you think it's something in the Linux kernel and want
to check another OS... do an install, or try in ram...

https://download.freebsd.org/ftp/snapshots/amd64/amd64/ISO-IMAGES/12.1/
Pick latest -rnum-memstick.img.xz
xzcat | dd of=stickdev
boot
shell
ifconfig -a
ifconfig <dev> n.n.n.n/mask
route add default g.g.g.g
man resolv.conf
pkg install cdparanoia
or
fetch http://pkg.freebsd.org/FreeBSD:12:amd64/latest/All/cdparanoia-3.9.8_10.txz
LD_LIBRARY_PATH=./lib ./bin/cdparanoia
mkdir /tmp/rips
mdmfs -s 1g md /tmp/rips
dmesg | egrep '(da|cd).*device|sectors'
cdparanoia /dev/... to /tmp/rips or /dev/null

https://freebsd.org/ports/
https://www.freebsd.org/handbook/
See also cdrtools-devel to test another ripper.