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question - is dual core worth the money?
http://forum.linhes.org/viewtopic.php?f=2&t=12732		 Page 1 of 1
Author:  bouncey [ Sun Nov 26, 2006 4:47 pm ]
Post subject:  question - is dual core worth the money?
Have any of you noticed much benefit to running mythtv on a dual core/processor setup? How much of the system parallelizes nicely? What about with commercial flagging and transcoding?

I ask because a 2.2 GHz AM2 "Orleans" amd64 is $92 at NewEgg, but it's only $60 more for a dual core "Windsor" at 2 GHz. :mrgreen:

Oh yeah... What's the difference between Orleans and Windsor from a myth user's point of view?

Edited to add: How much worse is the heat with dual-core? Any luck making extra cores sleep or slow down when not needed?
Author:  jimmyfergus [ Tue Nov 28, 2006 12:31 pm ]
Post subject: 
I don't have a good answer, but I have to imagine dual core helps. I'm planning on a dual core upgrade to give plenty of headroom to run VMWare virtual machines. It's easy to install VMWare Server, for the Linux-able at least. Then it's easy to create, for instance, a mail and web server, which is easy to preserve after a Knoppmyth upgrade.

Of course, for a bunch of VMs, you need a bunch of memory too. How come volatile memory is about US$100/Gb, whereas flash memory is about $20?

[url]silentpcreview.com[/url] is a great place for info on power consumption, particularly the forums. I think the dual cores do pretty well at idle, and if you get the right motherboard there's potential to automatically underclock/undervolt at idle too (dual or single core).

On the other hand, if you're doing SD, and nothing else with your machine, my guess is you might as well save the $60.

Sorry I'm light on specific info...
Author:  bouncey [ Tue Nov 28, 2006 3:02 pm ]
Post subject: 
I went ahead and ordered a dual-core AMD64, because eventually I'd like to try some HDTV. Also, my experiments with a slower AMD over the weekend showed that transcoding even a half-hour show to a more portable file format spanks the CPU for a long time.

I found the silentpcreview forums already. Saw some posts there that generally said the dual-core AMDs don't use much more power or generate much more heat than single cores. Lots of other fun advice there about cooling and noise reduction...

This processor is listed as a relatively low power/heat processor. We should find out in a week or so how well it works.
Author:  Girkers [ Tue Nov 28, 2006 9:13 pm ]
Post subject: 
I currently use a HT P4 adn found that it works much better than my old P4 2.4 especially playing HD TV.

From what I have read about the intel core 2 duo processors the cores will sleep when not in use and they also share the cache, so if one processor needs more cache it can simply take it.

Apparently as to heat these are a bit more efficent than the older P4s as the voltage is lower and they are built (I think) on a 90nm scale.
Author:  alanpdodd [ Sun Dec 24, 2006 6:37 am ]
Post subject: 
Girkers wrote:
I currently use a HT P4 adn found that it works much better than my old P4 2.4 especially playing HD TV.

From what I have read about the intel core 2 duo processors the cores will sleep when not in use and they also share the cache, so if one processor needs more cache it can simply take it.

Apparently as to heat these are a bit more efficent than the older P4s as the voltage is lower and they are built (I think) on a 90nm scale.


Shared cache is not always good as both cores have to wait for the cache to use it.

On the whole though a HT system or dual core should be good for media type stuff as you can hit one core and have the other free to deliver other stuff, maybe another transcode.
Author:  graysky [ Sun Dec 24, 2006 7:05 am ]
Post subject: 
Is the KM kernel compiled to auto detect and manage a dual core CPU (I know 2.4x supports up to 32 processors, maybe I'll have a look at the changelog)? Is Mythtv a multithreaded app (i.e. will it actually use both cores on a dual core chip)?

To me, the second question is over arching most of today's home computing. In the windows world, I wonder what percentage of users who own an Intel dualcore or AMD X2 chip are actually running the 64-bit SMP version of XP. Furthermore, how many applications are actually written to use multithreaded hardware? I think some Photoshop plugins can do it, although Photoshop itself cannot as I understand it. What else does the average user do that would benifit from two cores AND is written for two cores?
Author:  tjc [ Sun Dec 24, 2006 10:47 am ]
Post subject: 
graysky wrote:
Is the KM kernel compiled to auto detect and manage a dual core CPU (I know 2.4x supports up to 32 processors, maybe I'll have a look at the changelog)? Is Mythtv a multithreaded app (i.e. will it actually use both cores on a dual core chip)?

1) Yes.
2) While neither the frontend or backend proper are multi-threaded, you've got multiple seperate processes involved (mysql, backend, frontend, X, ...) so YES.

BTW - You're already using asymetric multiprocessing, especially if you're using a PVR card or XvMC for playback.
Author:  ethernut [ Sun Dec 24, 2006 12:10 pm ]
Post subject: 
I have a AMD X2 4200+ Dual Core and can be transcoding two things while watching HDTV. Not bad.
Author:  ethernut [ Fri Dec 29, 2006 10:23 am ]
Post subject: 
Just for giggles and grins I thought I'd post this for illustration. The numbers in bold are percent of CPU used at that moment in time.

This TOP output is from my system MBE/FE (see my signature). Here I'm running a commflag on a previously recorded show (at High Priority mind you) while watching Discovery HD (Libmpeg2, OneField, No OpenGl Sync)

3806 mythtv 39 0 99004 50m 13m R 81 5.4 3:25.11 mythcommflag
3420 mythtv 0 0 562m 422m 124m S 62 44.7 3:15.71 mythfrontend



This is the same commflag job running while watching standard definition tv. (Libmpeg2, OneField, No OpenGl Sync)

3806 mythtv 31 0 99400 51m 13m R 100 5.5 3:45.43 mythcommflag
3420 mythtv 0 0 463m 324m 44m S 12 34.4 3:22.71 mythfrontend


Notice the importance of Dual Core in these instances.
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