Processor Scalability and Linux

[Roberto Ragusa]

JD wrote:
>   On 08/08/2010 01:15 PM, Roberto Ragusa wrote:
>> Are you going to really use a lot of CPU power? (such as video processing)
>> Probably not.
>>
>> If you are just planning to have a fast general-use computer, than
>> do not worry too much about the CPU, as AMD or Intel and 4 or 6 cores
>> will not make a real difference to you.
>> Consider buying a SSD disk for your operating system and your "live" data
>> plus an additional big traditional disk for your "storage" data.
>> I assure you that a SSD disk will have much more impact on the speed
>> of the machine.
>>
> Some years ago, I benchmarked a 32 bit application on
> 3 GHz Athlon 64 and 3GHz Pentium (was latest release at that time).
> Both machines running RHEL 4.
> The application consistently completed on the AMD in  half the time it
> took on the Pentium. The cause of the improvement was IMHO the
> CPU-Memory bus speeds of the AMD chip. The front side bus of teh pentium
> could not move the data as fast. And That app was very very cpu and
> memory intensive, with datasets as large as 3GB!!
> Furthermore, it was not a multithreaded app.
> 
> Nowadays, the multicore pentiums have sped up the FSB to respectable
> speeds of 1.6GHz or perhaps even higher. But I have not kept up with
> this area of the technology, so I could not address the very latest
> cpus from AMD and Intel.

What you say in some way confirms my point.
In an extreme CPU-bounded case (you said "very very"), the speed
ratio between the CPUs was about 2:1.

On the other hand, in extreme IO-bounded cases, the speed ratio
between the hard disk and a SSD can be 100:1.

Consider that I/O intensive tasks are more frequent than CPU intensive
tasks for the average computer user (just consider booting, folder
browsing, app loading, data loading, data searching, file copying, ...).
That is why money spent for a SSD is well spent.

What should one choose between (for about the same total price)?

a) a 40mq house plus a 300km/h car
b) a 4000mq house plus a 150km/h car

I would say: "go for a) only if you are in car racing, otherwise go for b)"

(note that I applied the 2:1 and 100:1 ratio).

-- 
   Roberto Ragusa    mail at robertoragusa.it