[mythtv-users] MythTV performance in a demanding real-life environment

Yeechang Lee ylee at pobox.com
Mon Apr 23 08:02:26 UTC 2007


I wrote a couple of weeks ago:
> As I previously mentioned in this thread, even over a network I
> routinely see three simultaneous commflags of HD programs proceeding
> at 60fps each (or about double the framerate for a 1080i recording),
> and with a local array I've seen triple-digit commflags (although I
> can't remember whether this was with a HD program).

Here's some more data on mythcommflag performance. With a 1.6GHz
Clovertown quad-core server with a local RAID 6 disk array (and also
running a single VMware instance); a remote RAID 5 disk array; and
gigabit Ethernet [1] linking the two:

For three simultaneous non-realtime commflag jobs on the Clovertown
server of:

* Remote digital-cable SD recordings:[2]

  Each job runs at 360-420fps using ~100% CPU (~60% during "searching
  for logo").

* Local digital-cable SD recordings:

  Each job runs at 375-420fps using ~100% CPU (40-60% during
  "searching for logo").

* Remote 1080i HD recordings:

  Each job runs at 60-70fps using ~100% CPU (likely lower during
  "searching for logo," but untested).

* Local 1080i HD recordings:

  Each job runs at 60-70fps using ~100% CPU (75-95% during "searching
  for logo").

[1] Over CIFS, from the RAID 5 server and with no other network
activity, I get 60MB/s writes to and 72MB/s reads from the RAID 6
array. This implies 50-60% utilization of gigabit, which isn't
bad. From the RAID 6 server, I get 36MB/s writes to and 72MB/s reads
from the RAID 5 array.[3]

[2] Necessitated by the fragile-mythcommflag phenomenon I noted at
<URL:http://www.gossamer-threads.com/lists/mythtv/users/258846#258846>.

[3] Which I built back in the day with a non-optimal chunk size. I get
36MB/s on local writes, too, although local reads hit 110MB/s.

-- 
Yeechang Lee <ylee at pobox.com> | +1 650 776 7763 | San Francisco CA US


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