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Resolve V9 maximum Ram question

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Paul mitchell
Resolve V9 maximum Ram question
on Apr 26, 2012 at 9:38:10 pm

now that V 9 will be 64 bit,( when it comes out this summer) could I max out my 12 core mac pro with 64GB Ram using all 8 slots?

or is there a limitation in pairing Ram in trios


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Juan Salvo
Re: Resolve V9 maximum Ram question
on Apr 27, 2012 at 12:44:56 am

@Dmitry it's not nonsensical, that actually is a good question. I don't know if you know anything about resolve, but in the previous 32bit version the memory usage was optimized for triple channel memory. So the recommended configs were 12/24/48. Now that the app has been rewritten in 64bit the way memory is handled has probably changed. Paul's question is actually an insightful & important one, that It didn't occur to me to ask the resolve product managers in my conversations with them.

The refresh rate question is clearly from a resolve lite user who is trying to use an unrecommended intensity card and a consumer tv set to monitor the output of a color correction app. It's a silly question that could be cause by dozens of issues, from which devices he's using, to how it's set up, to the cables and adapters he's got in the chain. And it's a waste of this forum to spend time trying to figure out where in the chain someone who hasn't taken color correction seriously enough to buy a sdi card and monitor went wrong. Maybe he should contact his LG set manufacturer.



online editor | colorist | VFX | BD author

http://JuanSalvo.com


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Rick Lang
Re: solve V9 maximum Ram question
on Apr 27, 2012 at 12:01:22 pm

If you are referring to the triple-channel access to memory, this is not altered by the application software being 64-bit. So a 12/24/48GB memory configuration will still provide the fastest access to all the memory. Of course you can still load and use 64GB but the access may revert to dual- channel. That may not be a bad thing if you really need to use the extra 16GB since having the extra RAM reduces the need to use virtual memory and swapping pages into real memory as required. I can't recalled the actual memory degradation when running in dual-channel mode but I saw BareFeats benchmarks years ago that demonstrated the hit was quite small in terms of overall performance. I suppose you could try 48GB and if that seems to be all your system typically needs, then stop there. If you find it frequently swapping pages, consider adding the extra 16GB and reducing your swaps.

Let me know if you have any supplementary questions in case this isn't clear.

Rick Lang

iMac 27” 2.8GHz i7 16GB


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Juan Salvo
Re: solve V9 maximum Ram question
on Apr 27, 2012 at 4:55:16 pm

Hi Rick,

I don't think the triple channel optimization is so much a product of hardware, as it is software. I believe it has to do with the way davinci engineers decided to work around the limitations of 32bit memory access.

In there recommended configuration they strongly suggest using either 12-24 or 48gb of ram. 64bit should actually change that, as the software would be able to access the entire ram of a system without having to account for the address limitations of 32bit.

I guess we'll find out when the revised configuration guide gets posted.

-Juan

online editor | colorist | VFX | BD author

http://JuanSalvo.com


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Rick Lang
Re: solve V9 maximum Ram question
on Apr 27, 2012 at 11:58:23 pm

[Juan Salvo] ”( don't think the triple channel optimization is so much a product of hardware, as it is software. I"

The reference to memory in the 8,2 Configuration Guide specifies 6, 12 or 24 GB for memory optimization (not 8, 16 or 32 GB). I’m confidant this is because the memory controller in the hardware uses triple-channel access for the most efficient access to the DIMMs. It’s not related to any 32-bit processor limitation that will go away when the DaVinci Resolve software runs in 64-bit mode. I’ve looked on ark.intel.com to try to find a nice summary of memory access but haven’t been able to find anything succinct for the Mac Pro as I downloaded when I bought my iMac in late 2009. The iMac is only dual-access, but there is a great discussion about multi-channel memory access in the (iMac’s) i7-800 intel data sheet. My prior post should still be accurate. Currently 48 GB could work in triple-channel access on a 12-core Mac Pro using 6 8 GB DIMMs but if 64 GB is installed, it will be dual-channel access and not recommended by Blackmagic.

Rick Lang

iMac 27” 2.8GHz i7 16GB


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Joakim Ziegler
Re: solve V9 maximum Ram question
on May 8, 2012 at 4:53:27 am

Resolve on Linux, which has been 64-bit for a while, still prefers 12/24/48 GB of RAM. So it's likely this is a hardware issue, although I'm uncertain how big the impact actually is.

--
Joakim Ziegler - Postproduction Supervisor


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