[MPlayer-users] pentium4 bench

[Arpi]

Hi,

> > note that p4 2hgz doesn't seem to be 2x (or more) faster than 1ghz celeron-2.
> > it's strange, as it has very fast ram (400mhz rambus compared to 133mhz sdram)
> > and also the cpu has double clockrate.
> > maybe the code should be optimized differently for p4?
> >
> 
> Not only, there's a lot of other stuff which is not sped up proportionally
> to CPU/FSB clock increase, like how fast are memory chips themselves?
> I bet they are internally the same 40-50ns SDRAM which gives you
> only marginal memory speed increase despite of FSB speedup. Also,

I doubt. 
- they have big cooling metal on the modules (a sthey are very hot)
- they run at 400mhz (instead of sdram's 133mhz)
- memtest86 shows 1120 MB/sec while it shows about 126 MB/s for PC133 SDRAM

so i think ram is more than fast.

afaik the biggest advantage of p4/rambus is high memory speed increase.

> CPU pipeline length vs branch misprediction may increase the cost of
> mispredicted branches eating up performance. All in all, you dont get
> twice the performance by simple two fold CPU/FSB clock increase,
> to get it, you have to increase the clock of all the components involved,
of course i know

> including I/O (PCI bus and cards on it, disks), memory chips, and so on.
why? at least if cpu and ram runs at double rate, and it doesn't use any I/O
(in/out data is in memory, no video display or other i/o to pci/agp bus)

the problem is what Michael said - p4 cpu is slower than p3 at same freq.


A'rpi / Astral & ESP-team

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