[mythtv-users] Is interleaving memory still the best bet for an Atom?

Raymond Wagner raymond at wagnerrp.com
Mon Jan 9 21:03:58 UTC 2012


On 1/9/2012 14:47, Matt Emmott wrote:
> A friend of mine is looking into the Zotac Zbox to replace a failed 
> Front End. I remember reading some discussion on this list that two 
> RAM sticks are better than one, as the interleaving will help video 
> playback performance.

You're talking about two completely different things.  A memory module 
is going to contain a number of banks, and each bank may be busy on some 
task at any given time.  If a bank is busy, a different bank can be 
accessed in the mean time.  In hard drive terminology, consider 
non-interleaved memory to be like a bunch of spanned drives, while 
interleaved memory to be like a RAID0 stripe.  Better for some types of 
load, worse for others, but really not something you should need to be 
concerned about.

On the other hand, one module versus two is about memory channels.  Most 
modern systems have two channels, while higher end ones can have three 
or four.  Two modules of DDR3-1333 on one channel will do 10GB/s, 
regardless of whether it is interleaved or not.  Two modules on two 
separate channels will do 20GB/s.

On older ION systems, the video chip ran off the system memory, and 
system memory became a real issue as some users found low speed memory 
would starve the decoder.  On newer ION2 systems, the video chip has 
dedicated memory, and since the CPU itself isn't doing much of anything 
(and doesn't have the power even if you wanted it to), memory 
performance isn't that important.  Of course, with memory as cheap as it 
is, there is no point to trying to save $10 by only getting one stick of 
memory.


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