Multiple virtual memory segments on HP-UX ...

... is well known to give pergormance problems. But can anyone direct me to any literature or exaplation as to why? thanks Neil

Hi, from a HP person, commenting on memory segments: "Our hardware provides only 2 registers to store the protection code for memory segments. The alternate usage of more than two shared memory segments results in "protection faults" and a reload of the register content. This will result in a higher CPU utilization and in decreased overall performance." For HP's 64 bit boxes (and with HP-UX 11), there seem to be 3 registers available, so 3 shared memory segments should be fine. There is probably more information available from http://www.docs.hp.com/ Hope this helps, Heiko Neil Truby wrote: > ... is well known to give pergormance problems. But can anyone direct me to > any literature or exaplation as to why? > > thanks > Neil

Check the latest version of the FAQ at www.smooth1.demon.co.uk Three registers is what HP PA-RISC processors i.e. 1 goes to Resident Segment 1 goes to 1st Virtual 1 goes to Message Segment Hence >1 Virtual causes a type of 'page faulting' on the segment protection registers.. Heiko Giesselmann wrote in message <3A0C7EBD.350DB16C@informix.com>... >Hi, > >from a HP person, commenting on memory segments: > >"Our hardware provides only 2 registers to store the protection >code for memory segments. The alternate usage of more than two shared >memory segments results in "protection faults" and a reload of the >register content. This will result in a higher CPU utilization and in >decreased overall performance." > >For HP's 64 bit boxes (and with HP-UX 11), there seem to be 3 registers >available, so 3 shared memory segments should be fine. > >There is probably more information available from http://www.docs.hp.com/ > >Hope this helps, Heiko > >Neil Truby wrote: > >> ... is well known to give pergormance problems. But can anyone direct me to >> any literature or exaplation as to why? >> >> thanks >> Neil >