[mythtv] [mythtv-commits] Ticket #2782: automatic simultaneous jobs scaling

[John P Poet]

On 12/8/06, osma ahvenlampi <oa at iki.fi> wrote:

<snip>

> This is why I referred to CFQ scheduling. With CFQ enabled and the
> jobs being niced, they won't be getting a whole lot of I/O bandwidth
> in this situation, so I really doubt that will be the thing taking you
> over the edge -- it'll be the too-many-recordings-and-playbacks alone
> that would be the real contributors, as you said (in the part I
> clipped).

IONICE is one of the cool things about CFQ

I experimented with using ionice to prevent auxiliary applications
from interfering with mythbackend, with very poor results.  "ionice
-c3" is suppose to set a process to only get I/O if the disk is idle.
This did not seem to match reality.

After some searching, I finally found where someone said that ionice
*only* effects READS.  WRITES are not effected.  Since my auxiliary
app was trying to write to the same disk that mythbackend was, using
ionice did not prevent the aux app from stealing write bandwidth from
mythbackend.

I assume commflagging does not do much in the way of disk writing, but
transcoding does.

<snip>

John