[mythtv] Loud hard drive due to NuppelVideoRecorder.cpp sync()

[Arthur Britto]

Another option to quiet newer IDE drives would be to use the -M option
of hdparm.

-Arthur

On Thu, 2003-06-12 at 22:25, Sam N. Max (snx) wrote:
> I am fairly new to MythTV, so please bare with me... :)
> 
> During recording or live recording my hard drive was getting very loud
> writing little bits of the video to the hard drive every second.  After a
> while I figured out that this had to do with the call to sync() in
> NuppelVideoRecorder::WriteVideo which gets called every keyframe (which is
> every second).  I imagine this was done to try to spread the load of any
> hard drive writes so there isn't a large write later on.  I commented the
> sync() out, and my hard drive settled down, and from what I can tell I
> wasn't having any trouble recording.
> 
> I'm not sure if I'm the only one has this hard drive noise problem.  It's
> not as big a problem when it's writing a long stream of bytes (i.e. a
> copying a huge file), but it has a problem with writing small bits every
> second as myth does.  Looking at the man page for sync() this causes myth to
> wait, which may end up wasting CPU time that could have been used encoding
> while the data gets sent to the hard drive (unless there's some
> multithreading going on to get around this).
> 
> Perhaps an option could be added to allow the user to specify whether sync()
> should be called.  I'm not sure about other users experiences, but it might
> make sense to not have it all (or default off).  If it used, there might be
> some gain in encoding speed by moving the call to sync into another thread,
> though that may prove useless.
> 
> One final thought.  Many people seem to have noticed a slow down with
> version 0.9 (for now I've been sticking with 0.8).  I haven't fiddled with
> it yet, but I was wonderring if the "position map" database write that
> occurs every key frame may be the culprit (it comes right after the sync()
> call in NuppelVideoRecorder.cpp).  There's also the call to the somewhat
> kludgy looking "KickDatabase" function which I'm not totally sure about...
> ;)
> 
> - Eron
> 
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