[linux-dvb] Re: artefacts in picture - where can I find the module options? 2nd try

["Rene Bartsch" <ML@Bartschnet.de>]

On Sa, 10.07.2004, 17:36, Jon Burgess sagte:
> Rene Bartsch wrote:
>
>>>I'm having artefacts in the picture (VDR). The HDD (SATA) performs with
>>>58 MB/s, so I assume it's related to the PCI-bus (on an i865PE board).
>>>
>>>
> My setup has an i865G running with 4 x Nova-T PCI cards and I don't see
> any problems so I suspect the PCI bus is not the cause.
>

Mine has three Novas (Satelco Standard DVB-S).

> Does "femon" report any frontend errors when you see the artefacts? You
> should be able to have femon running at the same time as VDR.
>
> Could you run "vmstat 1" while VDR is showing problems and reports a few
> lines of the output?
>

I'll check that when I'm back home tomorrow.

> I know of one problem when using a combination of  VDR + Linux-2.6 +
> ext2/3. This manifests itself in the vmstat output as a high CPU% as the
> "io wait".
>
> Is this a combination that you use?
>

Yes, it is. Using a kernel 2.4.22 everything worked fine. Then I upgraded
to 2.4.(don't know wether it was 24 or 26). This caused problems with the
buggy S-ATA/P-ATA modules. So I decided to directly go to 2.6.6 using
libata.
FS is Ext3. But the artefacts also appear when streaming (streamdev-server).

> VDR triggers a preformance regression in the 2.6 kernel by streaming
> lots of small writes to the filesystem.
> I did some benchmarks to demonstrate the problem a few months ago, but
> AFAIK it has not been fixed.
>

The three week old iptables-bug hasn`t been fixed, too (even Debian
doesn't provide patched kernels, yet). Things currently seem to slow down
in kernel development.

> To "fix" the problem I changed my video storage drive to use JFS. The
> benchmarking I performed showed that JFS, XFS and ReiserFS v4 are not
> effected by this issue.
>

Ok, I'll check vmstat and CPU load (although it shouldn't be a problem on
a HT-machine?). Would be glad if changing FS helps :-)

Thanx :-)

Rene