Re: cdrecord: DMA speed too slow
>From: scdbackup@gmx.net
>I found a way to slow down my writer drive (hdc) by simultaneously using
>my DVD-ROM (hdd). That produces DMA speed measurements of about 1500
>to 2500 kB/s.
>cdrtools-2.01a35 reports :
> Drive DMA Speed: 1435 kB/s 8x CD 1x DVD
> ...
> cdrecord: DMA speed too slow (OK for 8x). Cannot write at speed 10x.
> Starting to write CD/DVD at speed 10 in real TAO mode for single session.
>After a few minutes i stopped the reading process at hdd and cdrecord began
>to report speeds of 10.1x to 10.6x. Average speed was ~ 7x.
So you just verified, that even 8x was not possible ^^^^^^^^^
>Quite funny, nevertheless, is this message :
> Drive DMA Speed: 2429 kB/s 13x CD 1x DVD
> ...
> cdrecord: DMA speed too slow (OK for 13x). Cannot write at speed 10x.
> Starting to write CD/DVD at speed 10 in real TAO mode for single session.
>cdrecord was started with speed=10 . Why does it complain about speed 13x ?
Tnak you for the hint, cdrecord now uses the same reduced (for reserve) speed
ithe OK for part as for the computation itself.
>Now i kept the reading process alive during the whole burn of 589 MB.
>cdrecord reported speeds of 2.2x until suddenly it went up to 10.3x or 10.9
>after half of the CD was done. The DVD-ROM was busy all the time.
>After about 50 MB cdrecord slowed down to 2.0x again. Average speed was ~ 3x.
Looks like bad scheduling behavior from your OS. Cdrecord runs at highest
possible real time priority. THe OS should give it highest I/O priority for this
reason......
Jörg
--
EMail:joerg@schily.isdn.cs.tu-berlin.de (home) Jörg Schilling D-13353 Berlin
js@cs.tu-berlin.de (uni) If you don't have iso-8859-1
schilling@fokus.fraunhofer.de (work) chars I am J"org Schilling
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