Bug#567056: brasero: Brasero is very slow burning a data DVD-R

[Thomas Schmitt]

Hi,

>         growisofs
>         -use-the-force-luke=notray
>         -use-the-force-luke=4gms
>         -dvd-compat
>         -speed=8
>         -use-the-force-luke=tty
>         -Z
>         /dev/sr0=/proc/self/fd/0

Yes, it is growisofs working.
The options are ok for a burn run without mkisofs
being run by growisofs itself. (Normally it forks
mkisofs and writes its output to media. Here we
have the cdrecord-like use case of just burning.)


> 13238272/4422105088 ( 0.3%) @2.6x, remaining 27:45 RBU  88.3% UBU   7.3%
> 31457280/4422105088 ( 0.7%) @3.9x, remaining 20:56 RBU  70.1% UBU  98.8%
> ...
> 86081536/4422105088 ( 1.9%) @3.9x, remaining 15:57 RBU  15.8% UBU  98.8%
> 103514112/4422105088 ( 2.3%) @3.8x, remaining 15:17 RBU   0.0% UBU  67.4%
> 115638272/4422105088 ( 2.6%) @2.6x, remaining 15:31 RBU   0.0% UBU  24.4%

It is hungry for input.

RBU (= Ring Buffer Usage ?) is the fifo where
growisofs buffers the input. This one is always
low through the whole burn. Only at start it was
full.

UBU (= Unit Buffer Usage ?) is the drive's
buffer (1 or 2 MB). It oscillates between
0 % and 100 %. The latter happens only when the
drive is completely out of data and takes a
rest to wait for more input.

This pattern tells me that Brasero cannot feed
growisofs fast enough. Probably because its ISO
filesystem generator cannot gather its own
input fast enough.

Are there many small files involved ?
Or a slow disk from where Brasero shall read ?

------------------------------------------------

> cdrskin_log
> Track 01:    1 MB written (fifo 100%) [buf   0%]  13.8x.
> Track 01:    2 MB written (fifo 100%) [buf  93%]   0.2x.
> Track 01:    3 MB written (fifo 100%) [buf  93%]   3.9x.
> Track 01:    4 MB written (fifo 100%) [buf  99%]   3.9x.

Slow start. Contemporary burners begin with 6x.

> Track 01:  385 MB written (fifo 100%) [buf  99%]   3.9x.
> Track 01:  386 MB written (fifo 100%) [buf  99%]   0.3x.
> Track 01:  387 MB written (fifo 100%) [buf  99%]   6.1x.

Next speed zone reached. The burner accelerates.

> Track 01: 1537 MB written (fifo 100%) [buf  99%]   5.9x.
> Track 01: 1538 MB written (fifo 100%) [buf  52%]   0.3x.
> Track 01: 1539 MB written (fifo 100%) [buf  52%]  14.8x.
> Track 01: 1540 MB written (fifo 100%) [buf  98%]   8.7x.

Final speed of 8x reached ...

> Track 01: 4398 MB written (fifo 100%) [buf  98%]   8.0x.
> Track 01: 4399 MB written (fifo 100%) [buf  98%]   8.0x.

... and pertained up to the end.


Your drive and its bus connection are ok for 8x.
The problem is at the input side of the burn
program.


Have a nice day :)

Thomas