ATHLON vs XEON: number crunching

[Steffen Persvold]

On Thu, 20 Jun 2002, Velocet wrote:

> On Wed, Jun 19, 2002 at 06:09:17PM -0700, Bill Broadley's all...
> > On Wed, Jun 19, 2002 at 08:48:48PM -0400, Ivan Oleynik wrote:
> > > Yes,
> > > 
> > > Both Xeon and Athlon have 2GB PC2100 registered DDR.
> > > The code fits in 70 MB of RAM.
> > > 
> > > Ivan
> > 
> > Right, but many p4's, like the e7500 chipset based p4 dual motherboards,
> > use two banks of DDR, where as all todays Athlon duals use one bank of
> > DDR memory.  Sadly the only dual memory bus athlon I know of is nvidia's
> > low end desktop motherboard.
> 
> I swear someone just said in the other thread that the Tyan 246x was
> two banks of DDR... true?
> 

Well, the E7500 chipset has two DDR _channels_ while the AMD762 system 
controller has one DDR _channel_. One DDR channel is 64bit + ECC and is 
normally running at 133MHz which gives us a theoretical peak performance 
of 2.1 GBytes/sec per channel. However, the E7500 chipset is only able to 
run the memory bus at 100MHz and with the interleaving of the two channels 
that gives us a theoretical peak performance of 3.2 GBytes/sec.

I believe the term "banks" is related to the layout of the DIMMs and has 
nothing to do with the architecture of the system controller. 

Here are some stream numbers. The Athlon platform is Tyan S2466 equipped 
with two Athlon MP 1900+ (1.6 GHz), and the Xeon platform is SuperMicro 
P4DPR-6GM+ equipped with two Xeon 1.8 GHz (Prestonia).

Athlon, 1 process :

Function     Rate (MB/s)  Avg time   Min time  Max time
Copy:        877.5785      0.0365      0.0365      0.0367
Scale:       801.7857      0.0400      0.0399      0.0402
Add:         894.9042      0.0537      0.0536      0.0539
Triad:       887.2120      0.0542      0.0541      0.0544

Athlon, 2 processes :

Function     Rate (MB/s)  Avg time   Min time  Max time
Copy:       1385.1016      0.0236      0.0231      0.0253
Scale:      1345.9527      0.0242      0.0238      0.0250
Add:        1168.2247      0.0419      0.0411      0.0425
Triad:      1210.0117      0.0405      0.0397      0.0473


Xeon, 1 process :

Function     Rate (MB/s)  Avg time   Min time  Max time
Copy:       1898.8954      0.0170      0.0169      0.0181
Scale:      1813.9614      0.0179      0.0176      0.0186
Add:        1839.8592      0.0265      0.0261      0.0274
Triad:      1826.2738      0.0266      0.0263      0.0274

Xeon, 2 processes :

Function     Rate (MB/s)  Avg time   Min time  Max time
Copy:       1160.5962      0.0297      0.0276      0.0311
Scale:      1261.8243      0.0269      0.0254      0.0275
Add:        1237.7180      0.0395      0.0388      0.0407
Triad:      1231.9053      0.0398      0.0390      0.0405


Regards,
 -- 
  Steffen Persvold   | Scalable Linux Systems |   Try out the world's best
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