[mythtv-commits] Ticket #3757: Reduce polling in mythwelcome
MythTV
mythtv at cvs.mythtv.org
Thu Sep 27 18:18:22 UTC 2007
#3757: Reduce polling in mythwelcome
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Reporter: anonymous | Owner: ijr
Type: defect | Status: new
Priority: minor | Milestone: 0.21
Component: mythtv | Version: head
Severity: low | Resolution:
Mlocked: 0 |
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Comment(by drees76 at gmail.com):
Replying to [comment:11 candrews at integralblue.com]:
> According to powertop, the backend's polling rate stayed the same at
~16.5/sec on my computer.
> However, it helped in your setup (as it seems it did!) then that's even
better!
You'll notice in your "before" mythbackend shows up twice, once with 75
wu/s (schedule_timeout) and once with 16 wu/s (futex_wait). Your "after"
plot eliminates the mythbackend schedule_timeout wakeups completely which
is expected from the patch.
The mythbackend futex_wait wakeups are coming from somewhere else.
> I've been running the patch since I applied it on a backend/frontend
combo, and on a frontend
> only. I haven't noticed any bugs, and I've been using both to watch and
record tv, do live tv,
> watch videos, etc.
Great! That's what I expected. Hopefully the devs can push this patch
upstream!
> As for the strace, that was taken with the patch applied. I'm presently
trying to figure out
> how to use gdb to figure out where in the code those selects are taking
place, but not being a
> C programmer or someone who has ever used gdb is making that difficult
:-)
The other way is to simply read the code and look for places where polling
out timeouts are used, but without being a C/C++ or a programmer at all
makes it a bit difficult. :-)
I haven't used gdb in a while myself, but what needs to be done is to
attach the process to the debugger and then print out a stack trace of all
the running threads. It should be apparent what threads are doing the
polling.
--
Ticket URL: <http://svn.mythtv.org/trac/ticket/3757#comment:12>
MythTV <http://svn.mythtv.org/trac>
MythTV
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