Re: Growisofs input cache --> Patch

[David Weisgerber <david.weisgerber@cs.tum.edu>]

On Tuesday 09 December 2008 21:48:25 Bill Davidsen wrote:
> David Weisgerber wrote:
> > Tested: 4x2742 MB
> >
> > Run 1 (w/o -no-directio): 5:37 min (for the slowest DVD recorder)
> > Mem:   2060284k total,   593336k used,  1466948k free,    15972k buffers
> >
> > Run 2 (w -no-directio): 4:38 min (for the slowest DVD recorder)
> > Mem:   2060284k total,  1877136k used,   183148k free,      224k buffers
> > ---
> >
> > In Run 1 there were several buffer underruns which slowed the DVD
> > recorders down. In Run 2 the buffer was always at 100% (except for the
> > end of course) :-).
>
> This seems reasonable, what were the performance numbers for the other
> system activity? I'm surprised at the underruns, cdrecord has internal
> fifo, and I thought you did, too. With a hacked cdrecord (around a50)
> the burn ran almost eight seconds slower, regardless of burn size, and
> never dropped below 92% full at the drive, and 70% or so in the fifo.

The underruns are not suprising. I am burning directly from a NFS share via 
Gigabit Ethernet and the server has a consumer class 1 TB hard drive. Even if 
I only run with 8x speed, it consumes 4 * 8 * 1.3 MB/s = 41.6 MB/s...
The first run needed 337s, this means it had an average data transfer rate of 
8.1 MB/s for each burner. This means the 4 burners altogether sucked 32.5 
MB/s in average. That's a good value for a consumer class network in my 
opinion...