[mythtv-users] Poor playback performance on Mac mini

Joe Nyland joenyland at me.com
Mon Mar 12 21:39:27 UTC 2012


On 12 Mar 2012, at 16:43, Raymond Wagner wrote:

> On 3/10/2012 16:51, Joe Nyland wrote:
>> 
>> Xeon E31230 3.2 GHz (Quad core +HT) CPU - 4 cores assigned to MythTV backend server
> 
> So that means MythTV has full access to the CPU?

Yes, that's correct.


>> Recordings stored on 3 1TB Seagate drives in md RAID5
> 
> Do you have your database on this same array?  What filesystem are you using?

No, the database is on my system drive, which is EXT4, barriers not disabled.


>> CPU usage is around 50% on my primary frontend when playing back recordings - I'm not sure this is all MythFrontend, but it proves the point that the CPU is not exhausted.
> 
> On the contrary.  It means you are using one full core of that 2.4GHz Core 2 Duo, and hitting a wall because something is single threaded.

Well, I say 50% - what the activity monitor of Mac OS shows is that both cores are running at around 50%.


> On Linux, that should be sufficient for CABAC H264 content at around 12-14Mbps, which is rather high for broadcast HD, and well beyond what you should be seeing for SD video. 

Exactly my thoughts. Furthermore, as I have mentioned, other (non-MythTV) 1080p content plays back on this system from the same server and disk array.


> Considering you are running the same version of MythTV and OSX on the iMac, is it having similar problems?

As I said, I am seeing no issues what so ever with the same build/dmg/app that I am copying to my Mac mini. Even if I run MythFrontend on my iMac (@2560x1440) playback of video is fine. This could just be tolerating an underlying issue better than my Mac mini, though, as it's a 1GB GPU...

I've just typed the above, then gone to check the CPU usage for your question below on my iMac. I set MythFrontend to the same resolution, as to get a fair comparison. I received the exact same behaviour on my iMac, which I hard reported from my Mac mini only. :-(

I set the resolution on my iMac back to full screen (2560x1440) and it's smooth again... It may seem strange, but to me, it seems like 1920x1080 resolution which is causing issues, or some reason, only in MythTV.


> What is the CPU usage during playback?

CPU usage for MythFrontend on my iMac is fluctuating between 60%-80%. As far as I am aware, this percentage is the percentage for one CPU core, either way, I feel it's a bit steep would you agree
CPU usage for MythFrontend on my Mac mini is 60%-70%

>> RAM usage hovers around 2GB mark on my primary frontend.
> 
> Well that simply doesn't sound right.  Even at 1080p and an artwork intensive theme, you shouldn't be hitting half that.  Are you reading the resource usage, or the virtual memory allocation?

I've checked my RAM figures and again to get it right: 
RAM usage for MythFrontend on my iMac is 205Mb.
RAM usage for MythFrontend on my Mac mini is around 240Mb.

Please disregard my 2GB RAM figure from before.

Sorry this is a little disjointed. I hope I've provided the info required.

Thank you for your time.

Joe
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.mythtv.org/pipermail/mythtv-users/attachments/20120312/e3d350d2/attachment.html 


More information about the mythtv-users mailing list