On Fri, Jul 3, 2009 at 5:07 PM, Jay Reynolds Freeman<jay_reynolds_free...@mac.com> wrote: > On Jul 3, 2009, at 1:20 PM, Greg Guerin wrote: > >> [useful comments excised, thank you very much] > > I will try lseek and write at the end. > >> Exactly what problem is solved by initially writing multiple >> gigabytes of zeros to disk? > > As for what I am doing, I have a parallel Scheme system (Wraith > Scheme, see the "Software" page of my web site, URL in the .sig), > and I use mmap to obtain a shared Scheme main memory. By > "parallel", I mean separate Unix processes, not threads. I am > setting things up so that a user who wishes to do so can choose > a memory size large enough to drag the application to a screeching > halt from swapping, and the way to do that seems to be for one > process to create a file of the desired size, then have that > process and all the others mmap it. I am not saying that it is > wise to choose such a large Scheme main memory, but some users > may want to do it. > > If there is a better way, I would love to hear about it; I am > by no means an mmap wizard.
You can do shared memory without requiring the entire shared memory space to be backed by a file on your hard drive. There is a POSIX API for shared memory which you can get to by googling "POSIX shared memory" or looking up the man page for the shm_open function. You can also do shared memory using mach calls, but I don't actually know what those calls are. Mike _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
