HyperThreading makes worse to me (was Re: How to reproduce: Re: Only 70% of theoretical peak performance on FreeBSD 8/amd64, Corei7 920)

Thu Apr 15 08:29:38 UTC 2010

May I make a suggestion?

Would you mind creating a shared google spreadsheet with your testing
results and a shared google document with the test setup?

I think having the data in an easily represented, easily shared medium
would be beneficial to everyone.

Adrian

On 15 April 2010 08:46, Maho NAKATA <chat95 at mac.com> wrote:
> Hi Andry and Adam
>
> My test again. No desktop, etc. I just run dgemm.
> Contrary to Adam's result, Hyper Threading makes the performance worse.
> all tests are done on Core i7 920 @ 2.67GHz. (TurboBoost @2.8GHz)
>
> Turbo Boost off, Hyper threading off: 82% (35GFlops)    [1]
> Turbo Boost off, Hyper threading off: 72% (30.5GFlops)  [2]
>
> Turbo Boost on,  Hyper threading on: 71% (32GFlops)    [3]
> Turbo Boost off, Hyper threading off: 84-89% (38-40GFlops) [4]
>
> ---my system---
> CPU: Intel(R) Core(TM) i7 CPU         920  @ 2.67GHz (2683.44-MHz K8-class CPU)
>  Origin = "GenuineIntel"  Id = 0x106a5  Stepping = 5
>  Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
>  Features2=0x98e3bd<SSE3,DTES64,MON,DS_CPL,VMX,EST,TM2,SSSE3,CX16,xTPR,PDCM,SSE4.1,SSE4.2,POPCNT>
>  AMD Features=0x28100800<SYSCALL,NX,RDTSCP,LM>
>  AMD Features2=0x1<LAHF>
>  TSC: P-state invariant
> real memory  = 12884901888 (12288 MB)
> avail memory = 12387717120 (11813 MB)
> ACPI APIC Table: <110909 APIC1026>
> FreeBSD/SMP: Multiprocessor System Detected: 4 CPUs
> FreeBSD/SMP: 1 package(s) x 4 core(s)
> ---my system---
>
> ---DETAILS---
> [1]
> % ./dgemm
> n: 3000
> time : 57.666717 or 16.339074
> Mflops : 33060.624827
> n: 3100
> time : 61.502677 or 16.597376
> Mflops : 35910.025544
> n: 3200
> time : 69.075401 or 19.199833
> Mflops : 34144.297133
> n: 3300
> time : 73.699540 or 19.633594
> Mflops : 36618.756539
> n: 3400
> time : 82.256194 or 22.373651
> Mflops : 35144.518837
> n: 3500
> time : 88.975662 or 24.118761
> Mflops : 35563.394249
> n: 3600
> time : 96.436652 or 26.027588
> Mflops : 35861.148385
> n: 3700
> [2]
> % ./dgemm
> n: 3000
> time : 139.622739 or 17.693806
> Mflops : 30529.327312
> n: 3100
> time : 154.344971 or 19.566886
> Mflops : 30460.247702
> n: 3200
> time : 169.507739 or 21.467100
> Mflops : 30538.116602
> n: 3300
> time : 186.363773 or 23.615281
> Mflops : 30444.600545
> n: 3400
> time : 203.798979 or 25.817667
> Mflops : 30456.322788
> n: 3500
> ...
> [3]
> % ./dgemm
> n: 3000
> time : 134.673079 or 16.958682
> Mflops : 31852.711082
> n: 3100
> time : 148.410085 or 18.663248
> Mflops : 31935.073574
> n: 3200
> time : 162.835473 or 20.468825
> Mflops : 32027.475770
> n: 3300
> time : 179.025370 or 22.479189
> Mflops : 31983.262501
> n: 3400
> time : 195.859710 or 24.663009
> Mflops : 31882.208788
> n: 3500
> [4]
> % ./dgemm
> n: 3000
> time : 54.259647 or 14.684309
> Mflops : 36786.204907
> n: 3100
> time : 60.899147 or 17.124599
> Mflops : 34804.447141
> n: 3200
> time : 64.295342 or 17.490787
> Mflops : 37480.577569
> n: 3300
> time : 69.781247 or 18.288840
> Mflops : 39311.284796
> n: 3400
> time : 79.234397 or 21.829736
> Mflops : 36020.187858
> n: 3500
> time : 83.905419 or 22.381237
> Mflops : 38324.289174
> n: 3600
> time : 92.195022 or 25.105942
> Mflops : 37177.621122
> n: 3700
> time : 97.718841 or 25.434243
> Mflops : 39841.319494
> n: 3800
> time : 105.740463 or 27.414029
> Mflops : 40042.592613
> n: 3900
> time : 113.980157 or 29.678505
> Mflops : 39984.635420
> n: 4000
> time : 122.941569 or 31.946174
> Mflops : 40077.412531
> n: 4100
> ---DETAILS---
>
>
> From: Adam Vande More <amvandemore at gmail.com>
> Subject: Re: How to reproduce: Re: Only 70% of theoretical peak performance on FreeBSD 8/amd64, Corei7 920
> Date: Wed, 14 Apr 2010 11:34:45 -0500
>
>>> > time : 162.488885 or 20.430651
>>> > Mflops : 32087.318295
>>> > n: 3300
>>> > time : 178.497079 or 22.446093
>>> > Mflops : 32030.420499
>>> > n: 3400
>>> > time : 195.550715 or 24.586152
>>> > Mflops : 31981.873273
>>> > n: 3500
>>> > time : 213.403379 or 26.825058
>>> > Mflops : 31975.513363
>>> > n: 3600
>>> > ...
>>> > above output is on Core i7 920 (2.66GHz; TurboBoost on)
>>>
>>> My results:
>>> $ ./dgemm
>>> n: 3000
>>> time : 54.151302 or 28.189781
>>> Mflops : 19162.263125
>>> n: 3100
>>> time : 60.157449 or 32.214141
>>> Mflops : 18501.570537
>>> n: 3200
>>> time : 65.753191 or 34.114872
>>> Mflops : 19216.393378
>>>
>>> CPU:
>>> CPU: Intel(R) Core(TM)2 Duo CPU     E7300  @ 2.66GHz (2653.35-MHz K8-class
>>> CPU)
>>>  Origin = "GenuineIntel"  Id = 0x10676  Stepping = 6
>>>
>>>
>>> Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
>>>
>>>  Features2=0x8e39d<SSE3,DTES64,MON,DS_CPL,EST,TM2,SSSE3,CX16,xTPR,PDCM,SSE4.1>
>>>  AMD Features=0x20100800<SYSCALL,NX,LM>
>>>  AMD Features2=0x1<LAHF>
>>>  TSC: P-state invariant
>>> ⋮
>>> FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs
>>> FreeBSD/SMP: 1 package(s) x 2 core(s)
>>>
>>> FreeBSD:
>>> FreeBSD 8.0-STABLE r205070 amd64
>>>
>>> Please note that the system was not dedicated to the test, I had
>>> Xorg+KDE3+thunderbird+skype+kopete+konsole(s) plus a bunch of daemons
>>> running.
>>> That probably explains irregularities in the results.
>>>
>>> I am not sure how exactly theoretical maximum should be calculated, I used
>>> 2 *
>>> 2.66G * 4 ≈ 21.3G.
>>> And so 19.2G / 21.3G ≈ 90%.
>>>
>>> Not as bad as what you get.
>>> Although not as good as what you report for Linux.
>>> But given the impurity and imprecision of my test…
>>>
>>> P.S. the machine is two-core obviously :-)
>>> Don't have anything with more cpus/cores handy.
>
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