2011-05-20 3:30 GMT+02:00 erik quanstrom <quans...@quanstro.net>: > one note is that while i'm aware of privalloc(2), i didn't use it. the > implementation doesn't appear correct for shared-memory procs. > i think there are two issues > - locking is unnecessary. the only preemptable unit of execution is > a process and each process is guarenteed to have its own instance > of _privates and _nprivates. > - for shared-memory procs, we will run out of privates because > the static privinit will be falsely shared. privinit should be replaced > by using a private entry. >
In a set of processes that share memory, I need a single per-process location to store the address of structure (which is in turn allocated in the global memory space). Privalloc(2) seemed what I need, but seem that I can't use it properly. In the parent process I do: 1) initialialize a global variable p = (MyStruct **)privalloc(); 2) allocate a MyStruct for every process I'm going to spawn 3) spawn processes with rfork(RFMEM|RFPROC) The spawn() function that call rfork takes a MyStruct* as argument and assign it to *p in the new process. For extra safety I added an assert(*p == nil) just after rfork, and after a few (apparently?) successful spawns, the assert fails. What I need is a sort of thread-local storage for the MyStruct*, so that each child process can find it's own dedicated MyStruct. I know that could get this with an hashtable based on the pid, but I'd prefer to avoid the book keeping if possible. Giacomo
