[Pkg-libburnia-devel] Bug#567056: brasero: Brasero is very slow burning a data DVD-R

[George Danchev]

Quoting "Thomas Schmitt" <scdbackup at gmx.net>:

Hi,

> Hi,
>
> Leandro Lucarella:
>> > > Burning some files in a data DVD using brasero is very slow. I get 2.6x
>> > > speed at most and my drive is 8x capable. Using growisofs directly,
>> > > i get a 6.6x speed average (which seems reasonable for a 8x drive).
> Josselin Mouette:
>> > My guess goes for a bug in libburn; one specific to the drive, since I
>> > haven't noticed such a slowdown with my 16x burner.
> George Danchev:
>> Thomas, do you have any rough idea what might be the cause for such low
>> rates to be picked as compared to growisofs?
>
> We had a hunt for speed in November.
> One of my USB drives was slower with libburn
> than with growisofs. Users had similar problems.

Leandro, could you please tell us whether libburn was actually used  
for burning and which version it was.

> The reason is not really clear. External drives
> changed their speed when being plugged into
> another computer. eSATA was faster than USB with
> the same drive and computer.
> growisofs did not always outperform libburn.
>
> With some drives speed got improved by using
> libburn ./configure options
>   --enable-dvd-obs-64k
> or
>   --enable-track-src-odirect
> and then
>   make clean ; make

Thomas,
I'm not actually sure whether these options would affect the rest of  
the drives and use cases in an unpredicted way. If they are safe, I'm  
more than happy to enable them in the next package upload, so that the  
library users would benefit as well.

> Without compiling, one may also use cdrskin or
> xorriso for experiments.
>   cdrskin ... dvd_obs=64k ...
>   xorriso ... -dvd_obs 64k ...

Leandro, testing with cdrskin and xorriso and these options (see man  
for examples) would help us to deduce whether the source of that  
slowness has anything to do with libburn itself. Could you please  
provide us with your results?

> Inside Brasero one could use for testing:
>   void burn_write_opts_set_dvd_obs(struct burn_write_opts *opts, int obs);
> with obs = 65536 .
> The call is available since libburn-0.7.4
> (december 2009).
>
>
>> product: LITE-ON DVDRW SOHW-832S
>> logical name: /dev/hda
>
> Are there any indications that DMA might not
> really be in effect ?
> (Hopping cursor, high CPU load with "WAIT".)
>
> Do you get better throughput if running the
> program as superuser ?

Okay, however, the reporter said the speed was fine with growisofs, so  
if it was a DMA settings it would also affect growisofs burning job.