[mythtv-users] 32 vs. 64 bit, any significant difference?

Rod Smith mythtv at rodsbooks.com
Wed Dec 16 20:40:09 UTC 2009

On Wednesday 16 December 2009 11:26:31 am Brian Wood wrote:
> Building a new backend, and trying to decide whether to go 32 or 64 bit.
> Obviously it's a 64-bit CPU (AMD FX-60).
> Only using 2GB of RAM, so that's not a factor.
> I know it's been asked before, but reviewing past posts I don't seem to see
> any final conclusion.
> Normally I'd go with 64 bit, but I wonder of there are any reasons to go 32
> (Flash players, XBMC Boxee)?

I've recently done a number of upgrades -- Ubuntu 6.04 (32-bit) to 9.10 
(64-bit), MythTV 0.21 to 0.22, and some hardware upgrades. I did the 32-bit 
Ubuntu 6.04 to 64-bit Ubuntu 9.10 first, and I noticed that playback of HD 
content when the system was doing other work (commflagging or transcoding) 
went from mostly watchable with perhaps one brief playback stutter every 
couple of minutes to completely stuttery. I don't know if that's really a 32- 
vs. 64-bit issue or if it has to do with library or binary differences or 
even some subtle setting somewhere (I duplicated all the original settings as 
closely as I could, particularly for X; the hardware was unchanged at this 
point, and I used the same MythTV database, so its settings were all 
identical). Overall, I'd say there's a good chance that there's some code 
somewhere in the chain that's better optimized for 32-bit x86 vs. 64-bit 
x86-64, but I can't be certain of that.

After I upgraded my CPU and motherboard (from a single-core Celeron-D 3.06 GHz 
to a dual-core Celeron E3300 2.5 GHz), the playback problems vanished. I'm 
not sure how fast your AMD FX-60 is relative to either of the CPUs I used, 

Rod Smith

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