1 2 Previous Next 25 Replies Latest reply on Oct 5, 2007 4:58 PM by sizarraga

    2 cpu Dual Core Vs 1 cpu Quad Core

    espiga Enthusiast

      I am implementing a Solution VI 3 and  with 2 dl380 g5 from HP what's  the best choice ? 1 Quad core CPU or 2 Dual core CPU ?

        • 1. Re: 2 cpu Dual Core Vs 1 cpu Quad Core
          BlueDragon Enthusiast

          Technical :

           

          2 Dual Core CPU (because of INTEL MULTIPLE CORE architecture) is a better choice than 1 Quad core CPU. The difference will be...not perceptible for ESX Server (as long as you've got a strong motherboard for this architecture)

           

          Financial :

           

          1 Quad CPU only need :

          \- 1licence for ESX

          \- 1licence for VMotion

          \- 1licence for VCB

          \- etc.

           

          2 Dual CPU need :

          \- 2 licence for eSX

          \- 2 licence for Vmotion

          \- 2 licence for VCB

          \- etc.

           

          So

           

          => If the price of 1licence for ESXVmotionVCB is cheaper than the difference between 2Core and 4CORE, take the 2CORE

          => Else, take the 4CORE

           

          Kingest regards,

          Seb.

          • 2. Re: 2 cpu Dual Core Vs 1 cpu Quad Core
            espiga Enthusiast

            OK Tanks but the problem is finance but is not on the license but in price off 2 dual core versus 1 quad core , because 1 quad core its more cheaper than 2 dual core the all solution is with 4 dl380g5 , i just need to understand if the performance is not halted

            • 3. Re: 2 cpu Dual Core Vs 1 cpu Quad Core
              citrix_guy Expert

              The perfromance wont be halted, but it wont be the same either. While you ahve 2 dual cores, and 4 total cores, you have to slots... to paths for the information to flow to other parts of the server systems (memory, disk etc etc).

               

              Also lets say (and just usign a number here) that you only get 80% of the perfromance on a second core (not a 2x increase over a single core proc for overall perfromance). Then in a dual core 2 socket system you have:

              100%80%100%+80% = 360

              Oon a quad core (again jsut an example not real numbers)

              100%80%80%+80% = 340

              Operations that are core heavy (tcp operations etc) like more cores. Operations that are going to use a lot of memory, tons of disk IO etc, I would still be worried about the number of sockets somewhat.

               

              So is there a HUGE perfromance hit? depends, probably not HUGE but it depends on the types of work you will through at this.

               

              Another thign to consider is that I think Vmware only officially supports at least 2 sockets installed even if you could get a quad core single CPU to run.

               

              Ron

              • 4. Re: 2 cpu Dual Core Vs 1 cpu Quad Core
                espiga Enthusiast

                OK Ron that help a lot

                • 5. Re: 2 cpu Dual Core Vs 1 cpu Quad Core
                  oreeh Guru

                  There was a nice article in the german iX magazine comparing SMP performance of Intel quad-core versus AMD dual-core.

                  I know that an Intel - AMD comparison is like an apple - pear comparison, but the results are nevertheless interesting.

                  Quad-cores are good at number-crunching but loose significantly when memory and I/O comes into play.

                  And in ESX we need memory and I/O.

                  The issue with the quad-cores seems to be the memory interface.

                  • 6. Re: 2 cpu Dual Core Vs 1 cpu Quad Core
                    kreischl Expert

                    I was looking at these charts yesterday and found them very interesting:

                     

                    http://www.tomshardware.com/2006/12/06/quad-core-xeon-clovertown-rolls-into-dp-servers/page7.html

                     

                    The issue though is if the Intel design on the quad core is poor enough where it will impeded any benefits when the vmkernel is trying to swap the code in & out.

                     

                    Message was edited by:

                            kreischl

                    • 7. Re: 2 cpu Dual Core Vs 1 cpu Quad Core
                      oreeh Guru

                      unfortunately most of these benchmarks are either "number-crunching" benchmarks or desktop related

                      • 8. Re: 2 cpu Dual Core Vs 1 cpu Quad Core
                        kreischl Expert

                        That is true...but I didn't expect the quad core to be slower in that many tests.

                        • 9. Re: 2 cpu Dual Core Vs 1 cpu Quad Core
                          oreeh Guru

                          I expected it for a few reasons

                           

                          The quad core cache architecture is more complicated

                          The memory / I/O bus is a limiting factor (4 cores competing instead of 2)

                          The chipsets are newer and (probably) buggier

                           

                          Most applications aren't SMP aware / aren't able to really use SMP.

                           

                          To get good results with 4 cores, you have to use highly optimized code and therefore use compiler settings you normally won't use for production.

                          • 10. Re: 2 cpu Dual Core Vs 1 cpu Quad Core
                            RParker Guru

                            Umm.. no.

                             

                            While the cores may require additional pathways, EACH core has it's own pathway to the memory.  So the peformance of a quad core is actually FASTER than ANY dual core, even if they are separate.

                             

                            Just because you have 2 sockets, does not imply 2 SEPARATE paths to memory, bus, and PCI.  They still share the path.

                             

                            Quad Core is much faster than Dual core, even in real world tests, and especially ESX.  AMD is faster than Intel for pure memory operations, but that is another story.

                             

                            But your numbers are off.  A core isn't like hyperthreaded processors, not sure where you got that info, a core is a core, period.  They are full processors.

                             

                            That being said, that in this scenario yes a Dual Core (if they are separate sockets) is better than a single CPU quad core, because of the point of failure, but that would be the only reason.

                             

                            Quad core is more expensive, but not by much.  Quad core, even though slower per core, is more efficient.  The overall speed you get is far and above that of dual core, 2 processors.

                            • 11. Re: 2 cpu Dual Core Vs 1 cpu Quad Core
                              oreeh Guru

                              EACH core has it's own pathway to the memory.

                               

                              this definitely is not true

                              They share the 3rd level cache - how could they have separate paths?

                               

                              Xeons are UMA systems.

                              • 12. Re: 2 cpu Dual Core Vs 1 cpu Quad Core
                                RParker Guru

                                That's not what this says.. and I have more numbers..

                                 

                                "After Effects comps, the quad core machine beat the dual core in every single test, but wasn't able to best two of the benchmark results of the Dell single-processor Core 2 Extreme machine running at 2.93GHz we tested a couple of months ago. But after those small defeats, the Clovertown machine couldn't be touched again by any of our contenders, especially with the Nightflight After Effects composition, which was devised to show the power of the Macintosh over the PC using extensive vector graphics rendering. The quad core machine crunched through that in 14:23, besting its closest competitor by more than 25%.

                                "

                                 

                                http://videoediting.digitalmedianet.com/articles/viewarticle.jsp?id=83846

                                 

                                Plus even VM ware has whitepaper that shows that Quad Core is WAY better than Dual Core.  Maybe OTHER apps can't take advantage of SMP, but we aren't talking about them, are we?  We are talking about VM Ware, which is the \*ONLY* thing that matters.

                                • 13. Re: 2 cpu Dual Core Vs 1 cpu Quad Core
                                  RParker Guru

                                  Hmm.. you need to read up on Quad Core Architecture then.

                                  • 14. Re: 2 cpu Dual Core Vs 1 cpu Quad Core
                                    oreeh Guru

                                    I meant 2nd level cache

                                     

                                    In the Intel specs there's the following sentence

                                     

                                    Processors employ Intel® Advanced Smart Cache (shared cache).

                                     

                                    With a shared cache it is impossible to have separate mem paths due to cache coherency implications.

                                     

                                    Message was edited by:

                                            oreeh

                                         

                                    and f you take a look at the Intel datasheets

                                     

                                    Four 32-KB Level 1 data caches

                                    Two 4 MB Level 2 caches

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