Re: [Problem] slow write to dvd-ram since 2.6.7-bk8

[Tino Keitel <tino.keitel@gmx.de>]

On Wed, Feb 16, 2005 at 23:29:24 +0100, Droebbel wrote:
> On Mi, 2005-02-16 at 22:55 +0100, Droebbel wrote:
> >Some new information:
> >
> >2.6.7 is ok, 2.6.7-mm2 is not ok, 2.6.7 with just the linus-patch from
> >mm2 is ok, 2.6.7 with linus.patch from mm3 isn't.
> >So I took some of the patches from the broken-out mm2 and tested them
> >seperately.
> >
> >The vmscan-dont-reclaim-too-many-pages.patch led to the said reduction
> >of writing speed. I reverse-applied it to 2.6.8.1, where it seems to
> >solve the problem.
> 
> Sorry, have to correct that: it seemed to help at my tests with dd
> (write 1G of zeroes to a file). Copying a file with mc still shows
> around 1.4MB/s. Could be worse, but is definitely not ok. It *is* better
> with 2.6.7.

Here are some numbers with my setup. I always wrote 1 GB of data to the
same DVD-RAM disc (EMTEC), to the device directly and to a fresh ext2
on
the disc.

kernel 2.6.10:

$ time { sudo dd if=/dev/zero of=bigfile bs=64k count=16000 ; sync ; }

real    32m5.025s

$ time {sudo dd if=/dev/zero of=/dev/cdrom bs=64k count=16000 ; sync ;}

real    29m41.980s

kernel 2.6.7:

$ time { sudo dd if=/dev/zero of=bigfile bs=64k count=16000 ; sync ; }

real    13m23.688s

$ time {sudo dd if=/dev/zero of=/dev/cdrom bs=64k count=16000 ; sync ;}

real    13m14.609s

Regards,
Tino