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Re: Speed of Mathematica on AMD machines

• To: mathgroup at smc.vnet.net
• Subject: [mg126480] Re: Speed of Mathematica on AMD machines
• From: "Oleksandr Rasputinov" <oleksandr_rasputinov at ymail.com>
• Date: Sun, 13 May 2012 03:03:22 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• References: <jog00v$g1d$1@smc.vnet.net> <joi3kq$n3s$1@smc.vnet.net>

On Sat, 12 May 2012 09:51:17 +0100, A Retey <awnl at gmx-topmail.de> wrote:

>
> Hi,
>
>> In the past, Intel had been known to engage in anticompetitive practices
>> with respect to AMD, and quite rightly was subject to legal penalties  
>> for
>> this. (Specifically, they encouraged large computer manufacturers such  
>> as
>> ...
>> which both show that Bulldozer performance is a very mixed bag in  
>> general.
>> While there are a few applications in which it can match or only just
>> outperform Intel's offerings, for the most part it falls behind them
>> considerably.
>
> Very good points, Oleksandr, I agree with everything except that you
> could argue just as well that the the performance of intels processors
> is a mixed bag, after all they could be expected to be faster where
> Bulldozer matches or outperforms them.
>

Technically that's true, although I think a factor worth considering is  
that Sandy Bridge and Bulldozer are not exactly contemporaneous. Sandy  
Bridge was launched in January 2011, while Bulldozer didn't come along  
until October of the same year. Recently Intel has released Ivy Bridge  
which improves again on Sandy Bridge performance (in general, but  
especially in respect of graphics).

> I think the point is that processors (and more important: bundles of
> hardware+OS+software) _are_ different and there is not a single number
> which you can reliably use to compare them -- your best deal depends on
> what exactly you are doing. That's not a very new finding though, you'll
> find that conclusion everywhere (actually whether that conclusion is
> made is a good measure of quality and impartiality of what you read).
>

I agree and will confess to being biased toward scientific and HPC  
benchmarks as I think that these are some of the only ones for which more  
performance still really matters for the average user (of these sorts of  
applications, which is admittedly a very small segment of the market as a  
whole). Compiling code is another example. Consumers in general are more  
sensitive to performance in mass-market applications such as media  
encoding/decoding and videogames. For symbolic computations in Mathematica  
we need large, fast caches and good performance in single-threaded integer  
workloads (characteristics that are shared by code compilation and  
videogames), and for numerical computations good memory bandwidth and  
multithreaded floating-point performance are called for (in common with  
HPC workloads and to some extent video encoding). In both cases Intel  
processors are a better match for Mathematica's requirements than AMD  
processors, which are more optimized for throughput in multithreaded  
integer workloads (although, if you make extensive use of the Parallel`  
package, AMD processors may be much more attractive).

> If you really try to find the optimal deal that's a tough job, and I
> think even experts can't do reliable forecasts without some
> experimentation on the real thing. Fortunately processors are so fast
> nowadays that you can get done quite a lot even with a poor choice...
>

I would definitely advocate doing your own benchmarks, but the specific  
ones mentioned by Dmitry are not likely to be very representative of  
general usage. MathematicaMark is not too bad, although I think it would  
be substantially improved by including some more involved tests such as  
integration, equation solving, expression simplification, numerical  
optimization, code compilation, plotting data and functions, and so on  
alongside the rather simple operations that make up the existing  
benchmark. In terms of representativeness, there is of course no  
substitute for benchmarking your own code. It is also very important to  
consider the ratio of performance/price, if cost is a factor. By this  
metric the AMD processors do not look as poor as they do when considering  
absolute performance. Power consumption is another relevant metric in many  
cases but AMD is again usually behind Intel here.

Best,

O. R.