Am Do, den 08.01.2004 schrieb Bevan C. Bennett um 19:38: > I suspect a full answer to this may be too involved for this list, but > maybe someone a little more into kernel hacking than I've been lately > could point me in the right direction. > > I have two identical servers, one running FC1 and one running severn > (RHEL3beta). The installed kernels are: > > kernel-smp-2.4.22-1.2138.nptl (FC1) > kernel-smp-2.4.21-1.1931.2.399.ent (severn) You mean not Severn, which was a Fedora beta, but you mean Taroon. I just checked that over the kernel version you give and that matches. > I have a very highly multithreaded application that runs generally 4x > slower on FC1, but occassionally takes 20x as long. Interestingly, the > "user" time in all cases is very consistant, and on the non-FC1 system > real time is only fractionally higher than user time. So... I suspect > that there's some kernel parameter, memory management scheme or > scheduling configuration difference causing the performance disparity. 4 times up to 20 times faster on Taroon compared to Fedora Core 1 is amazingly. Are you running one specific multithreaded application or a set of those? How do you measure the time it takes - by "time program"? > My question is whether there's any hope of discovering which difference > is involved and 'fixing' the FC1 system (or even of easily enumerating > what the differences actually are)? The RHEL kernel is very optimized for big machines with much RAM, multiprozessors and so on. Can you describe your machine park a little bit? > I know that FC is aimed more at a desktop/general user release (and is > the best Linux I've used so far for that purpose), and that ideally I'd > help support RedHat by purchasing 100 copies of RHEL for my heavy > computing, but there are unfortunate budgetary forces involved that > prohibit that at the moment. If the company situation improves, that's > the way I'd like to go eventually. > > I'm willing to compile custom kernels for a 4x speedup and better > consistancy, but I'd like to keep the number of different distributions > in active use to a minimum (every different distribution adds more work > in creating and maintaining compatible configuration info). > > Any informed suggestions from the community? Maybe you should post you question on the fedora-devel list. It seems the Redhat folks are paying there more attention to such questions than here. Regards Alexander -- Alexander Dalloz | Enger, Germany PGP key valid: made 13.07.1999 PGP fingerprint: 2307 88FD 2D41 038E 7416 14CD E197 6E88 ED69 5653
