[mythtv-users] Mythfrontend idle cpu consumption help
steven at openmedia.co.nz
Mon Nov 9 21:50:31 UTC 2009
On 9/11/2009, at 6:56 PM, Jim Stichnoth wrote:
> On Tue, Nov 3, 2009 at 1:34 PM, Jim Stichnoth <stichnot at gmail.com> wrote:
> I again used the Intel VTune performance analyzer to have a look, when
the overall performance degraded after the machine was up a few days.
All the time was being spent in the sunrpc module, particularly the
rpcauth_lookup_credcache and generic_match functions. A web search
shows that this is a known NFS problem in the 2.6.27 kernel, which what
I'm using (MythDora 10.21).
> My frontends are diskless NFS clients, so I guess this makes sense, and
may even explain why the problem gets worse over time and
> restarting the frontend doesn't help.
> Then I used "strace" to see what files are being accessed. Turns out
it's all a stat64 of /etc/localtime, about 70 times per second. I don't
know if this is something Myth is doing directly, or indirectly through
Qt. But if I set the TZ environment variable to the correct value (in
my case, 'America/Los_Angeles') and restart the frontend, the
performance problem mostly goes away. Running VTune again to monitor
the "idle" main menu shows mostly stuff related to the 70Hz Pulse loop
which I pointed out previously.
> So setting the TZ environment variable to the appropriate value before
starting the frontend may be another thing to try for people seeing
sluggish UI performance *and* an unexpectedly high CPU usage when
sitting at the main menu.
Some interesting analysis there, but is anyone else also seeing an
increase in memory use by mythfrontend over time
top - 22:15:18 up 2 days, 12:41, 5 users, load average: 0.17, 0.27, 0.17
Tasks: 216 total, 1 running, 213 sleeping, 0 stopped, 2 zombie
Cpu(s): 4.6%us, 3.3%sy, 0.0%ni, 92.0%id, 0.2%wa, 0.0%hi,
Mem: 1996004k total, 1946236k used, 49768k free, 40716k buffers
Swap: 875532k total, 320012k used, 555520k free, 971780k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
2714 mythfe 20 0 1020m 171m 15m S 15 8.8 482:38.99
1455 mythtv 20 0 450m 41m 9944 S 2 2.1 32:10.37
Here I have an Athlon 5050e which is currently running at 1GHz under
Mythbuntu 9.10. As has already been mentioned mythfrontend is doing
around 15% cpu.
Now the frontend process has been up for a couple of days and now has a
virtual memory footprint of over 1GB which I personally consider
somewhat extreme. Is this to be expected under 0.22?
Steven Ellis - Technical Director
OpenMedia Limited - The Home of myPVR
email - steven at openmedia.co.nz
website - http://www.openmedia.co.nz
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