Hi I'm having trouble understanding your question. Are you comparing CPU-time of a real VAX(which model?) to emulated CPU-time on an Itanium machine(which one?).
Emulation will have an associated overhead. If you are compareing a fast VAX to an emulation on a slow Itanium... well, Itanium is hard to optimize for. /P On Tue, Mar 05, 2019 at 03:13:53PM +0100, gérard Calliet wrote: > Hello, > > Again I have some performance issues with simh. > > I built it on OpenVMS Itanium. It runs on a process with enought > memory, it takes 1 of the 8 CPU Itanium with 100%, no page faults, > and 100 BIO by second. > > On the emulated VAX we are running processes CPU intensive (old Ada > compiler), they take 100% of the CPU, also very few page fault, very > few IO. > > And the CPU time is about 2 or 3 times the CPU time on the hardware, > and so elapsed time 3 or 4 times. (For my understanding, it is > difficult to think the same stream of instructions can use different > CPU times between hardware and SIMH). > > Where can I do something to improve performance? Are there > parameters (or constant in compilation) in SIMH which could help? > And the specific context is processes doing almost only CPU > computing. > > > >>>> my configuration, and what commit I use > on error continue > load -r ka655x.bin > attach NVR ka655.nvr > set cpu 512m > set cpu conhalt > set RL disable > set LPT disable > set TQ disable > set -L rq0 rauser=18000000 > attach rq0 datauser2.dsk > set xq mac=08-00-2B-3C-96-75 > attach xq eth0 > dep bdr 0 > b cpu > > > $ run vax-i64 > MicroVAX 3900 simulator V4.0-0 Beta git commit id: 8810571d > sim> > > > >>>>>>>>>>>>>> > > Thanks, > > Gérard Calliet > > _______________________________________________ > Simh mailing list > Simh@trailing-edge.com > http://mailman.trailing-edge.com/mailman/listinfo/simh _______________________________________________ Simh mailing list Simh@trailing-edge.com http://mailman.trailing-edge.com/mailman/listinfo/simh
