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787flyer

big.LITTLE impact on P3D performance - Intel 12th gen CPU?

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12 hours ago, Luke said:

The scheduler… it needs to determine what threads are doing a heavy workload and transfer them to the big cores of the load isn’t transient.

cheers

 

We would not be amused if the sims main process runs on a little core.


i9-9900K@5,0   |  32GB 3200  |  2080TI  |  4K 55"  |  MSFS | P3D V5

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I'm going to have read up more on Intel's bit.Little, I'm just not seeing the advantage for desktop computing.  It seems to be about power efficiency yet the 12900 is a 228 Watt unit vs. AMD 141 Watt unit?  What am I missing?  All I'm getting out of it is less intense tasks go on the little cores while more intense tasks go on the bigger cores ... so why/how is that going to improve performance overall?

However, it seems Windows 11 will adjust the schedule to benefit Intel's big.Little according to this article.  I just don't understand how the lower performing cores is somehow a benefit in performance?

Cheers, Rob.

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4 hours ago, Rob_Ainscough said:

I'm going to have read up more on Intel's bit.Little, I'm just not seeing the advantage for desktop computing.  It seems to be about power efficiency yet the 12900 is a 228 Watt unit vs. AMD 141 Watt unit?  What am I missing?  All I'm getting out of it is less intense tasks go on the little cores while more intense tasks go on the bigger cores ... so why/how is that going to improve performance overall?

However, it seems Windows 11 will adjust the schedule to benefit Intel's big.Little according to this article.  I just don't understand how the lower performing cores is somehow a benefit in performance?

Cheers, Rob.

Rob, I have been wondering the same which is why I posted the question.

Having done some more reading up, it could be that with the new design and a move to smaller wafer sizes, higher clock speeds could potentially result, but again I have read that that advantage may also be put towards making the cores more efficient in operation aka reduced power consumption, so the gain is not a given at this stage.

 

The other possible benefit , although personally I think this is somewhat limited where P3D is concerned, the new design will offer additional threads to run those processes.  e.g.

If you have 8 core CPU today which is capable of running 16 threads with HT turned on, potentially the equivalent CPU when Alder Lake arrives is 8 BIG cores (with HT on)  which equates to 16 threads plus potentially another 8 cores that can be made available by Windows based on the Little cores (no HT available), so in essence you have 24 threads at your disposal (16 +8) .

So theoretically you have 8 more threads to play with, but of course can P3D really take advantage of all those available? In another forum post (I think it was Ray's) I had the impression that while P3D and its concurrently running add-ons could be spread across other, less heavily used cores, adding more and more cores (threads) has a diminishing rate of return. I guess it all depends upon how many other add-ons you run concurrently with P3D and this will differ from user to user.

 

And of course there are other things to consider with moving to this new Intel platform in that:

  • you will need to invest in a new motherboard that can host the new LGA1700 CPU socket needed (+ CPU cooler kit/adapter)
  • there's still open debate about the DDR5 memory but it also likely to be super expensive if it is supported by Alder Lake
  • and from what I can tell PCIe 5.0 is still some way off even if a new motherboard can offer it, the GPU suppliers need to play catch up and even when they do, its likely to be ultra expensive graphics card.

 

Therefore, in my opinion, even if the performance advantage and power saving warrants the move up, I think its going to be a very expensive rig at the end of the day.

 

Best,

  • Like 2

Mark Aldridge
P3D v5.1 HF1 and sometimes FSX!

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@787flyer I tend to agree with you Mark.  I've been intending to do a rebuild from my 9700k rig to the alder lake.  I saw the big/little news and was not too excited as it appeared it was heavily focused on power saving.  But I am going to keep an open mind. 


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Posted (edited)
Quote

.....Ultra expensive graphics card....

So, no change there then :wink:

Edited by Christopher Low

Christopher Low

UK2000 Beta Tester

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Posted (edited)
8 hours ago, Rob_Ainscough said:

I'm going to have read up more on Intel's bit.Little, I'm just not seeing the advantage for desktop computing.  It seems to be about power efficiency yet the 12900 is a 228 Watt unit vs. AMD 141 Watt unit?  What am I missing?  All I'm getting out of it is less intense tasks go on the little cores while more intense tasks go on the bigger cores ... so why/how is that going to improve performance overall?

However, it seems Windows 11 will adjust the schedule to benefit Intel's big.Little according to this article.  I just don't understand how the lower performing cores is somehow a benefit in performance?

Cheers, Rob.

Rob, there are performance hybrids and efficiency hybrids possible. Alder Lake is a performance hybrid.

Karl

Edited by kaha

i9-9900K@5,0   |  32GB 3200  |  2080TI  |  4K 55"  |  MSFS | P3D V5

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1 hour ago, kaha said:

there are performance hybrids and efficiency hybrids possible

Yes, but what exactly is providing the performance?  The big.LITTLE architecture doesn't seem to be hugely relevant to where the performance is coming from ... like you indicated "performance hybrids".

In terms of P3D, XP, MSFS, AF2, I haven't seen any benefit going beyond 8 real cores ... the main core that has to manage all the threads and keep everything sync'd with a "physics time" (simulated world time) ... if the main core is pegged at 100% utilization all the time, more cores will just make matters worse in terms of FPS.  All flight simulators I've used operate of a main thread from which all other threads are created and terminated.

So perhaps my question is really, what has changed in Intel's "big" (performance hybrid) side of the physical CPU?

Cheers, Rob.

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1 hour ago, Rob_Ainscough said:

...So perhaps my question is really, what has changed in Intel's "big" (performance hybrid) side of the physical CPU?

Cheers, Rob.

Right! Probably nothing (well, they got faster). I'd be ok with those 8 big cores only.

Karl


i9-9900K@5,0   |  32GB 3200  |  2080TI  |  4K 55"  |  MSFS | P3D V5

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Posted (edited)

There are tests suggesting the 12900K is 10% faster on W11 than on W10. But I doubt that P3D would perform as much better on W11.

 

Edited by kaha

i9-9900K@5,0   |  32GB 3200  |  2080TI  |  4K 55"  |  MSFS | P3D V5

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