[mythtv-users] Disk activity at end of recording

[Jack Perveiler]

Hello,

When recordings stop (the recording... not playing back a recording) I get a
flurry of disk activity for a second or two... usually enough to cause a
stutter for a second if I'm watching a HD recording at the same time.  So if
I'm watching a HD recording I can pretty much count on some jitter every half
hour as recordings finish.

Some info about my system:

0) P4 3.0 GHz w/Hyperthreading (HD playback consumes about 70% processor)
1) Tuners are HD-3000 and PVR-500 (usually the HD-3000 and one of the 500
tuners is recording)
2) File system is 200 GB XFS LVM local to the machine (combination
frontend/backend).  DMA is on (UDMA5).  Output from hdparm:
/dev/hda:
 multcount    = 16 (on)
 IO_support   =  1 (32-bit)
 unmaskirq    =  1 (on)
 using_dma    =  1 (on)
 keepsettings =  0 (off)
 readonly     =  0 (off)
 readahead    = 256 (on)
 geometry     = 30515/255/63, sectors = 490234752, start = 0

3) No transcoding or commflagging is going on (they're restricted to when I'm
sleeping).

So now for my questions:

1) Does myth do some sort of minimal post-processing when a recording finishes?
 Or is this just the OS flushing the remainder of the buffer to disk and
closing the file?  Is this maybe something that XFS is just slow at?

2) I see in one of the frontend setup pages you can set the size of a HD buffer
to help "weather backend storms" (or something like that).  Is this one of
those cases?  If not, what exactly is that setting for?

Thanks,

--Jack



		
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