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=B3The pSeries 650 features a peak aggregate memory to L3 cache bandwidth of 25.6GB/second for an 8way configuration. In addition, aggregate I/O bandwidth is up to 16GB/second. The result is a remarkable combination of system architecture, speed and power that delivers efficient and cost-effective data sharing and application throughput.=B2 That=B9s a total of 25.6GB/s for 8 CPUs, or 3.2GB/s per CPU. 3GHz P4 Xeons typically have an 800MHz memory bus with double the speed at 6.4GB/s result (800MHz x 8 bytes per L2 cache line =3D 6.4GB/s). Furthermore, the speed at which the P4 Xeon can load data into L2 cache from memory is matched to the bus because the L2 cache line width is 8 bytes wide and can stream data to L2 at full bus speed. That said, I find typical memory bandwidth for the P4 in applications is limited at about 2GB/s. See here for more detail: http://www.cs.virginia.edu/stream/standard/Bandwidth.html In fact, looking at the results there, the IBM 650m2 only gets 6GB/s on all 8 CPUs. I wouldn=B9t be surprised if the strange L3 cache architecture of th= e IBM 650 is holding it back from streaming memory access efficiently. Whether this has anything to do with your problem or not, I have no idea! - Luke --B_3227266232_639298 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable <HTML> <HEAD> <TITLE>Re: [PERFORM] pg 8.1.3, AIX, huge box, painfully slow.</TITLE> </HEAD> <BODY> <FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-size:14.0px'>Gavin= ,<BR> <BR> On 4/7/06 2:24 PM, "Gavin Hamill" <gdh(at)laterooms(dot)com> wrote= :<BR> <BR> <FONT COLOR=3D"#0000FF">> I did look into the specs of the system, and the= memory bw on the<BR> > pSeries was /much/ greater than the Xeon - it's one of the things that= <BR> > really pushed me towards it in the end. I forget the figures, but it<B= R> > was 3 or 4 times greater.<BR> </FONT><BR>
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