[mythtv-users] Memory usage under 0.16

[Steve Hill]

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Ever since upgrading to MythTV 0.16 I've noticed a high memory usage - 
it's quite a problem because it causes parts of Myth to get pushed into 
swap and when they get paged back into memory the disk thrashes and causes 
the backend to drop frames - sometimes so badly that the frontend hangs 
when it gets to the affected bit of the recording.

I've attached some of the output of top below - obviously not all the 
reported virtual memory used by Myth is actually swap (some of it will be 
mmapped files), but there must still be quite a lot that _is_ in swap - I 
have 256MB of RAM which I would've thought is enough (always has been 
before upgrading to 0.16), but ATM the machine is exceeding the RAM size 
by 150MB once you take buffers and caches out of the equation:

- ------
top - 00:00:20 up 117 days,  7:00,  3 users,  load average: 3.93, 2.85, 
2.64
Tasks:  49 total,   1 running,  48 sleeping,   0 stopped,   0 zombie
Cpu(s): 44.6% us,  2.3% sy,  0.0% ni, 53.1% id,  0.0% wa,  0.0% hi,  0.0% 
si
Mem:    257104k total,   253656k used,     3448k free,    31436k buffers
Swap:   506036k total,   234636k used,   271400k free,    44828k cached

   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
  2207 root      10  -5  486m  93m  40m S  0.0 37.1   7:57.59 mythbackend
17189 root       6 -10  136m  45m  38m S  0.0 18.2   0:07.27 mythfrontend
17161 root      15  -1 91604  10m  69m S  0.0  4.0   0:29.83 X
- ------

On a slightly related note, when something hits the hard drive hard during 
recording, the backend does drop frames - I have DMA turned on on the 
drive, so am I right in thinging that a process with a higher nice 
shouldn't be able to steal the CPU from a less nice process when it hits 
the drive?

  - Steve       Jabber: steve at nexusuk.org     Web: http://www.nexusuk.org/

      Servatis a periculum, servatis a maleficum - Whisper, Evanescence

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