[vdr] Thread priority of cutting thread in vdr

Ludwig Nussel ludwig.nussel at gmx.de
Tue Oct 11 11:31:18 CEST 2005


Klaus Schmidinger wrote:
> Emil Naepflein wrote:
> >On Mon, 10 Oct 2005 09:54:56 +0300, Marko Mäkelä wrote:
> >
> >>On Mon, Oct 10, 2005 at 06:52:12AM +0200, Emil Naepflein wrote:
> >>
> >>>This is pretty useless on my system because the loss of responsiveness
> >>>is mostly caused by the disk accesses and not by cpu usage. 
> >>
> >>Are you sure that DMA disk transfers are enabled? If not, the copying
> >>with programmed I/O (PIO) will consume CPU.
> >
> >
> >As I wrote, there is no problem with cpu usage. And DMA is enabled as I
> >use a Promise SX6000 controller (SCSI interface). The main problem is
> >that the cutting thread reads and writes the data through the buffer
> >cache and purges useful data from the buffer cache. Any disk access when
> >using the menu then is delayed considerably. This is with a 2.4 kernel.
> >The 2.6 kernel behaves much better in this regard.
> 
> I'm currently in the process of adopting Ralf Müller's patch
> to avoid trashing the disk cache. Maybe that will help.

2.6.13+ also supports ionice. That could help to not starve other
processes accessing the disk. AFAIK it's on a per process level
though so the cutting thread would need to be turned into to a
separate cutting process.

cu
Ludwig

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