On Fri, Sep 07, 2001 at 03:18:55PM -0400, Green, Paul wrote: hi paul, thanks for responding.
> My advice is to avoid MAP_FIXED at all costs. absolutely love to. however, it's a speed improvement of a potential two or maybe even three orders of magnitude, and so cannot be ignored. and even then, i don't think it can be ignored. this is for an implementation of DCOM (which, if you remove the D it becomes COM, too :) it is necessary to describe data structures and functions using dce/rpc IDL. it is then necessary to pass these data structures, via the function calls, between processes, whether local or remote. the remote bit we have covered. ncacn_ip_tcp and ncadg_ip_udp (ConnectioN, DataGram, tcp/ip, udp). there, it doesn't matter if the passing of data structures is slow, because the network becomes the bottleneck, with order 1ms or greater response time. the local bit, suddenly things like packing a 1mb data structure into a buffer, only to pass it over with a memcpy or five over to another program on the same host, become significant. so basically, although i don't _think_ it's essential for the first implementation (wez will be able to correct me here), it's not something that can be left as-is. the implementation has, if you to are pass over data structures between programs, presumably in exactly the same way that those DB apps are doing, you must preserve pointers / memory segment offsets. and that means using MMAP_FIXED. if anyone has any better ideas, love to hear them. all best, luke