Hello. In my experience I have seen performance differences which are exaggerated by tightly coupled applications at scale (e.g. parallel high performance clusters). My tests were done implementing Perceus for cluster management, and I tried to use as many of the same external library components as possible (e.g. Intel Compilers, math libs, OFED, MPI, etc..). Because I was using many of the same runtime components (and even shared binaries) I didn't expect too large of a difference. I was wrong. Performance deltas that are virtually unmeasurable on single systems were compounded many times when running in tight unison at scale. At most we found 30% performance deltas between RHEL and Centos when running on just under 5k cores. Unfortunately time ran out so I wasn't able to also test SL. The reason for the difference that we found has to do primarily with the build environment that Red Hat uses. RHEL is not built on RHEL but rather a modified and highly optimized tool chain that is not distributed. It would be reasonable to assume that Fedora is also built using this environment. BTW, this is one of the reasons that after founding Centos I continued to also focus on a freely available high performance focused distribution of Linux (Caos Linux) that is tuned and tested for high performance (but lacks many of the packages as it is not general purpose, which for those requirements I now run SL). In the case of Fedora, you are also testing against a newer core library set and kernel both of which may further skew the differences. What benchmarks were you using to measure? What compilers did you use and what was the hardware (if you don't mind me asking)? Thanks for the insights and I am eager to hear if you are able to test with SL. Greg On Sat, Nov 28, 2009 at 9:11 AM, Lou Arnold <[log in to unmask]> wrote: > I wanted to know if the SL distribution was designed specifically to be fast. > > I am running a CentOS V5.3 and found that it is noticeably slower than > Fedora 11, to my great surprise. > > How does the SL distro compare for speed? > > I had planned to use the CERN or Fermi Lab version of SL if SL runs faster. > > -- > Lou. > -- Greg M. Kurtzer Chief Technology Officer HPC Systems Architect Infiscale, Inc. - http://www.infiscale.com