[mythtv-users] How much is too much CPU?

[Craig Treleaven]

At 10:40 PM +0200 6/3/13, Warpme wrote:
>On 5/31/13 2:36 PM, Craig Treleaven wrote:
>>I know, I know:  you can't be too rich or too thin or have too much 
>>CPU, but...
>>
>>So my master backend/frontend machine is a 4 year old 1.83 Core 2 
>>Duo.  It does OK but I'm really interested in http live streaming 
>>and it clearly won't keep up with that.  I could see serving up to 
>>3 HLS clients in our house between iDevices and wireless laptops. 
>>I'd like to buy something that will last another 4-6 years.
>>
>>Key loads on the machine:
>>-master backend recording and commflagging 1080i/720p MPEG2 streams.
>>-frontend
>>-MythWeb server
>>-HLS transcoding and serving (likely MythExpress)
>>-household fileserver (backups and shared pictures, etc)
>>
>>The box could be commflagging two recordings, displaying another 
>>program and transcoding up to three streams...and I'm sure 
>>mythfilldatabase would kick off at the same time!
>>
>>So, how much CPU would all that need?  Could a Core i5 Dual keep 
>>up? Core i7 Quad?
>>
>>I'd like to keep all these functions on one box because I don't 
>>have a good spot to locate another box.  Also, I think one beefy 
>>box is likely to cost less than two separate machines and chew up 
>>less electricity.
>>
>>Appreciate any experience that others can offer.
>>
>>Craig
>>_______________________________________________
>>mythtv-users mailing list
>>mythtv-users at mythtv.org
>>http://www.mythtv.org/mailman/listinfo/mythtv-users
>>
>Craig,
>
>Just my experience regarding CPU:
>Recently I decided to upgrade my BE from low power AMD platform 
>(235e CPU; 880G chipset) to Intel platform (DH67BL; i3 3220T cpu).
>BE is headless, has 6 tuners, 8G RAM and 10T storage (3x HDD)
>
>1. power consumption (measured at wall):
>idle 98..110 -> 68..77W
>load 115..120 -> 80..85W
>measured with 1600W-range kill-a-watt meter (so quantization errors 
>on beg.scale ADC are giving probably high errors. In future I will 
>measure power with ampero-meter (current) and look also with 
>oscilloscope on PFC)
>
>2. reschedules:
>for approx 78 channels, 500+ scheduled items: 6.0...6.5s -> 2.9...3.5s
>
>3. HLS transcode
>AMD was able to keep real time with up to 1080i->360p
>Intel gives me 1080->720p. 720p is OK; 768p is too much :-(
>
>4.Myth compile (KVM on BE host vs VMware on OSX Desktop)
>myth compile speed is comparable with my Desktop (quad Q6600 at 3.6G)
>
>Generally I'm highly surprised by Intel advantage over AMD: for 25% 
>less power it offers 3-5x more computing power (something like 
>2..2.5x from arch and next 1.5-2 times from HT).
>
>I do upgrade as business case shows me it is worth: assuming I will 
>sell on eBay my AMD Mobo/CPU with current prices (40-30% off) - 
>overall power savings (measured at wall) will give break even after 
>approx. 2,7y of 24/7 operation.
>
>Conclusions:
>-With today's electricity prices swap to v.effective arch like 
>Sandy/Ivy/Hasswell may make sense.
>-i3 3220T (35W dual 2,8G IB with HT) can keep HLS up to 720p
>-For general use, 35W IB CPU with stock clock is comparable with 
>~130W 50% OC quad Kentsfield (Q6600)
>
>I think You can consider SB/IB Intel chip.
>Next Q is about Your requirements regarding HLS.
>If 720p is enough - i3 3220T should be OK.
>If You need more - then You should go for i5/i7.
>In such case I will go for lower clocked i7 instead of higher 
>clocked i5 as i7 gives You HT. HT can greatly offset lower clock - 
>however lower clock means lower TDP. As HT in Sandy/Ivy is totally 
>different thing than in old "presshot" (look on my results with i3 
>with HT versus quad Q6600) - I strongly suggest i7 with clock like 
>1.8..2.2GHz.
>
>Hope it helps!

Thanks for the report.  I would not have guessed that an i3 had that 
much grunt!  What sort of bitrate are your 720P encodes?

Craig