Re: cpu comparison

On Mon, Jul 18, 2011 at 6:47 PM, Greg Smith <greg(at)2ndquadrant(dot)com> wrote:
> M. D. wrote:
>>
>> I'm a bit surprised as the x3450 has DDR3, while the E5335 has DDR2, and
>> of course because of the cycle speed difference alone I would think the
>> X3450 should beat the E5335.
>
> Try comparing them with stream-scaling to see what happens:
>
> https://github.com/gregs1104/stream-scaling
>
> You can't really test CPU performance in a simple way anymore; it varies
> depending on the number of processes running at once.  This test is the best
> way I've found to show how that works.  On a single thread, the X3450 may
> not be significantly better than the E5535.  But what should happen is that
> total speed keeps going up as you add more threads on the newer system,
> while the old DDR2 model stays as the same basic total.

By way of example we have a server with dual 6 core opterons that runs
on 667MHz memory and it maxes out the stream test with 8 threads,
getting no faster as you add threads. OTOH, our 4x12 core opteron
machines with 1333MHz memory and like 8 different channels to it,
scales right up to 40 or more threads running the stream test.