[Bug-xorriso] Burning on two drives at the same time slows down rate and xorriso crashes

[sean loony]

Hello,

this situation:
Two drives in my system.
One: On USB via USBtoSATA Adapter. Works without problems when used
alone
Two: On PCIe-SATA-Card, works without problems when used alone.

BUT when doing this:
Start a writing on the USB drive. Writing speed is in expected
range.
Now start another writing on drive two while the other is running.
Writing rate on drive one goes down to 0.1D and stays there till the
end. While writing on drive one, drive two has the same slow speed.
When one of each finishes the speed in the remaining drive reaches
normal speed.

I did this with a dvd-ram in drive one (non streaming mode, normal
writing speed is 1x), and other discs it doesn't matter.
Drive two was a dvd+rw, normal speed is 1-2x.
USB and SATA can handle this low speeds, theres no bottleneck at
this slow speeds.

I did another test:
USB drive: writing like above.
SATA-Drive: formating a new dvd+rw with dvd+rw-format

While formating, the rate of USB drive goes down to 0.1xD an after a
while to 0.0 and then xorriso freezed.
dmesg:
INFO: task xorriso:3744 blocked for more than 120 seconds.
[193932.477523]       Not tainted 4.10.0-35-generic #39-Ubuntu
[193932.477526] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" 
disables this message.
[193932.477529] xorriso         D    0  3744   3726 0x00000004
[193932.477533] Call Trace:
[193932.477546]  __schedule+0x264/0x740
[193932.477552]  ? text_poke+0x18/0x260
[193932.477556]  ? mutex_optimistic_spin+0x151/0x160
[193932.477559]  schedule+0x2e/0x80
[193932.477563]  schedule_preempt_disabled+0xd/0x10
[193932.477567]  __mutex_lock_slowpath+0x15a/0x290
[193932.477570]  mutex_lock+0x28/0x30
[193932.477575]  sr_block_ioctl+0x2e/0xb0
[193932.477578]  ? sr_block_check_events+0x30/0x30
[193932.477582]  blkdev_ioctl+0x9b2/0xb10
[193932.477586]  ? futex_wake_op+0x2a3/0x4c0
[193932.477592]  block_ioctl+0x39/0x50
[193932.477595]  ? bd_set_size+0xc0/0xc0
[193932.477599]  do_vfs_ioctl+0x91/0x6d0
[193932.477602]  ? __switch_to+0xa5/0x3e0
[193932.477605]  SyS_ioctl+0x60/0x70
[193932.477609]  do_fast_syscall_32+0x8a/0x150
[193932.477612]  entry_SYSENTER_32+0x4e/0x7c
[193932.477614] EIP: 0xb77b4cf9
[193932.477616] EFLAGS: 00000286 CPU: 1
[193932.477618] EAX: ffffffda EBX: 00000003 ECX: 00002285 EDX: b61fee0c
[193932.477620] ESI: b7390738 EDI: b73907d4 EBP: b73901a0 ESP: b61fed88
[193932.477622]  DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b
[194053.306986] INFO: task xorriso:3744 blocked for more than 120 seconds.
[194053.306994]       Not tainted 4.10.0-35-generic #39-Ubuntu
[194053.306996] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" 
disables this message.
[194053.306999] xorriso         D    0  3744   3726 0x00000004