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Re: growisofs + pipebuf2 = trouble

On Monday 23 February 2004 16:24 I wrote:

> So if it's a bug in pipebuf2, it only occurs under special
> circumstances...

...and that seems to be the case. :-( 

Whee, trashed all my media for nothing. I'm using pipebuf (not pipebuf2) 
now, with this it works just fine. Should have tried it earlier, sorry 
about that. I still can't figure out what's actually wrong with pipebuf2, 

My new command line now looks like this:

 (nice --5 cat DataDVD1.iso) | (nice --10 pipebuf -b 32767 -p) 
 | (nice --15 growisofs -dvd-compat -Z /dev/sr0=/dev/fd/0)

This uses a 32MB buffer with prefilling, which means that the buffer will 
be filled before the writing process starts. This avoids heavy loads in 
the first few seconds when using big buffers.

Oh yeah, the maximum buffer size pipebuf supports is actually 32MB, but if 
you need larger buffers it's no problem, since you can just stack another 
pipebuf on top of it. Just add another pipe. ;-)

The nice priorities are optional; without them I get speed issues when the 
system is under heavy (CPU) load. I use different nice values just to make 
sure that the buffer program can't eat the writing process' CPU cycles.

For me, this performs so much better than the plain method without buffer; 
writing speeds now stay constant at 4x, even if the system is under load. 
Before it occasionally broke down to slower speeds.


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