Package: cdparanoia Version: 3.10.2+debian-11 Severity: normal In a system with 2 SATA optical drives (have tried on two Jessie systems so-far), if two copies of cdparanoia are run simultaneously, and -d /dev/sr0 is specified on one copy, and -d /dev/sr1 on the other, then read performance drops to approx 5% of its normal speed. No errors are reported, and the operation completes successfully.
With 3 or more drives, the problem is exacerbated, and a single audio CD takes many hours to be read. In the test setup with just 2 drives, if either one or both of the copies instead use the corresponding /dev/sgX device (e.g.run lsscsi -g to obtain device node, or use sysfs), then both copies run at full speed. I assume this is a kernel bug, but thought I'd ask here first in case there was any known behavior within cdparanoia which could trigger this. Initial testing with a 3.2 kernel shows similar behaviour (although perhaps the slowdown is not so severe). I've reported this to the linux-scsi mailing list, but no response so far, it would be good to have a bit more certainty that this was a kernel bug. Reading the man page, it looks like cdparanoia uses the same interface (SG_IO ioctl) - however looking at the debug output, running against the /dev/sg interfaces seems to suggest that they expose scatter/gather, whereas the /dev/sr interfaces don't - perhaps this is sufficient to begin to explain the difference. I'll try and gather a bit more data, and report here (should be able to test with some IDE drives, and maybe a USB one to see if the problem persists. Incidentally, in the SATA test system, both optical drives are connected to different SATA host controllers. -- System Information: Debian Release: jessie/sid APT prefers testing-updates APT policy: (500, 'testing-updates'), (500, 'testing') Architecture: amd64 Kernel: Linux 3.16-2-amd64 (SMP w/2 CPU cores) Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8) Shell: /bin/sh linked to /bin/dash Versions of packages cdparanoia depends on: ii libc6 2.19-12 ii libcdparanoia0 3.10.2+debian-11 cdparanoia recommends no packages. cdparanoia suggests no packages. -- no debconf information -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
