Comments by: "A. Aoufi" who bought an R8K/75 Indigo2 Extreme and an R5000SC/180 Indy from me in February 2005, for use with his PhD work in computational chemistry, and to type up the thesis itself. He visited from France to collect the systems in person... ******************************************************************** Date: Fri, 4 Mar 2005 10:12:51 +0100 (CET) I was able to play mainly with the R8K, yesterday and I was very very very pleased. I was able to transfer a lot of my work into the sgi R8K. What a pleasure having all the compilers working. I thought that I have forgotten how to use it, but not at all, all my memories were intact. I used cvd and a lot of the stuff installed, but it will take a some times before I dig completely into all your goodies disk! I thank you a lot for the careful installation. [later...] Concerning the R8K / R5K. I have used them a lot and it appears that if I compile a program on the R8K with the -r10000 flag it generates a code that can be up to two times faster than the code generated without this flag. Amazing isn't it. In fact the fortran code I gave you, laplace runs four times faster on the R8K compared to the R5K. It delivers nearly 80 Mflops sustained, which is not that bad! The same code runs on the R12K@400Mhz at nearly 350 Mflops, which is amazing ( nearly 44% of the peak performance, and it is a sustained performance to solve a real problem). The R12K @ 400 Mhz is a jewel !!!! :D :D :D On the other hand, one of my C code runs only slighly faster on the R8K compared to the R5K which is still a good thing since there is a ratio of two in frequency between R5K vs R8K. I also learned that I need to rewrites some loops in my c-code and eventually convert it in fortran to test how I can increase the speed. Using sgi tools i was able to find out that I am ~15% below the ideal performance on the R8K. The same code on my 1.5 Ghz laptop runs ten times faster, so clock for clock the R8K is a very efficient cpu. It is also worth mentioning that the R12K@400 Mhz is only 7 times faster than the R8K on the same code. So definitely compared to this peecee that runs nearly four times faster, frequency wise, the mips R12K@400 is a beast. Definiteley the R8K is a mystery cpu. Once the code suits the architecture of the R8K, it can run very very fast. When I think that this cpu runs only at 75 Mhz. Cheers A.A.