[mythtv-commits] Ticket #9709: TFW IOBOUND

MythTV noreply at mythtv.org
Sun Apr 3 03:42:59 UTC 2011

     Reporter:  spamme@…               |      Owner:  danielk
         Type:  Bug Report - General   |     Status:  new
     Priority:  minor                  |  Milestone:  unknown
    Component:  MythTV - Recording     |    Version:  Trunk Head
     Severity:  medium                 |   Keywords:
Ticket locked:  0                      |
 I keep getting these messages at the start of recordings. Between 1 and 5
 (sometimes more) occurences at the beginning of every recording.

 TFW IOBOUND 5169 free(0) size (4194304) cnr(1)

 Normally, I assume that this message means your hard drive isn't good
 enough.  However, this is NOT the case.

   The OS and mysql are on 1 hard drive and recordings on another.

   I have a RAID 6 array with hardware controller, 4GB of RAM, and a AMD
 Quad Core 3Ghz processor dedicated to mythtv and general file storage.

 Assuming that 4194304 is a size in bytes, that is so small that it is
 useless, 4MB of buffer????  How do I increase this tiny number.  Since
 even the most humble hard drives should be able to push 40mb/s I would
 like a 40mb buffer.  Either that or a buffer that automatically expands
 and contracts as needed.

   I am especially concern because I have 4 HD tuners if 4MB isn't enough
 for 1 HDTV stream it certainly can't handle 4 at once.
   My lowest RAID 6 speed is 100mb/s write and 500mb/s read.  Typically
 write speeds are 200mb/s and read speed can reach 650mb/s.

   I found a "HD ringbuffer size" setting in mythtv-setup->General and I
 slowly cranked it up to its max of 96,256kb of ram to no effect.

   I have tons of system resources including TB of free space on the RAID
 and etc.  This message should not be happening to me.  Mythtv could use
 500mb of ram as a buffer and I wouldn't care, but getting IOBOUND on my
 system must indicate an inefficiency in the code.

   A HD recording is about 2-4mb/s each, and with modern hardware we should
 never be IOBOUND.  Ten concurrent recording should max at about 40mb/s a
 number well within any modern hard drives capabilities.

   I have extensively benchmarked all hardware and have upgraded to newer
 and faster equipment.  I am still getting TFW IOBOUND......  My hardware
 is WAY above what I should *need*.

Ticket URL: <http://code.mythtv.org/trac/ticket/9709>
MythTV <http://code.mythtv.org/trac>
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