Is anyone else seeing surprisingly weak performance on the hexacore chips?

[Michael Hodnett]

Greetings,

I can get into more specifics and details, but to start off this thread I just want to ask a fairly high-altitude question:

Does anyone else have experience with the hexacore processes in Linux?

We have a DL 580 G5, loaded up with 128GB of RAM and four hexacore processors (2.66GHz, with the 1066MHz FSB). We put RedHat 5.2 on it and loaded various databases (Oracle, Sybase, even Mysql). This server is consistently underperfoming a much weaker box--a DL 380 G5 with 16GB of RAM and 2 quad-core 2.66's (with a faster 1333MHz FSB)

Yes the bus speed is slower on the hexacore, but can this account for a very significant decrease in performance which is consistent at every load level (many threads or just a few at a time).

Could it be that the Linux kernel doesn't yet have proper optimizations for the hexacores? We've tried various RedHat-released kernels, and compiled our own from the latest linux.org source. We still can't get 24 total cores to work as hard as 8 total cores.

Any experience anyone's able to share with me would be greatly appreciated!

Mike