On Wednesday 16 May 2007, Andrew McIntyre wrote: > The place it is behind is on multi cpu machines. You even have to turn > hyperthreading off on xeon processors or it will run like a dog.
A common misunderstanding. Hyperthreading is of no use (even counterproductive) for database applications. Database applications are generally *not* processor intensive (unless re-indexing etc), but memory intensive. If you create *virtual* additional processors that try to access memory at the same time , all you do is hog the bus bandwidth and slow all processes down at the same time while waiting for memory access. Just compare real world performance on an machine without looking at the number of real or virtual processors used - run real world queries from real world clients simultaneously and measure time until results returned. Both MSSQL and Firebird will nowadays come close to the limits of your network capacity even in GB networks without coming anywhere near saturating processor capacity in nearly any conceivable real world situation unless the table structure/indices/queries have designed in mindbogglingly stupid ways. But Firebird will always use only a fraction of the resources MSSQL requires, and hence be faster on equal machines as long as the machines are not vastly overdimensioned for the task in which case MSSQL might have a minimal advantage. Btw, you will find that with most applications you will gain performance when switching off hyperthreading - HT is just a marketing gimmick for the gullible which only has advantage in very specific multitasking situations that do not require (much) bus access Behaviour of the server on multiple real processors is a different issue - mostly dependent on the underlying operating system. Like networking, SMP was always an afterthought in MS operating systems, carelessly bolted on, so no wonder that applications benefit little unless specifically optimized for SMP. Horst _______________________________________________ Gpcg_talk mailing list [email protected] http://ozdocit.org/cgi-bin/mailman/listinfo/gpcg_talk
