* Matt Dillon <[EMAIL PROTECTED]> [010930 14:59] wrote: > > : > :In message <[EMAIL PROTECTED]>, Matt Dillon writes: > :>: Second, application not always grows to 1G, most of the time it keeps > :>: as small as 500M ;). Why should we precommit 1G for 500M data? Doing > :>: multi-mmap memory management is additional pain. > :> > :> Even using file-backed memory is fairly trivial. You don't need to > :> do multi-mmap memory management or do any kernel tweaking. Just > :> reserve 1G and use a single mmap() and file per process. > : > :I once had a patch to phkmalloc() which backed all malloc'ed VM with > :hidden files in the users homedir. It was written to put the VM > :usage under QUOTA control, but it had many useful side effects as well. > : > :I can't seem to find it right now, but it is trivial to do: just > :replace the sbrk(2) with mmap(). Only downside is the needed > :filedescriptor which some shells don't like. > : > :-- > :Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > :[EMAIL PROTECTED] | TCP/IP since RFC 956 > > I think the file descriptor problem can be solved easily... simply > open the file, mmap() the entire 1G segment for this special application, > and then close() the file. Then have sbrk() just eats out of the mapped > segment. Alternatively sbrk() could open/mmap/close in large 1MB or 4MB > segments, again leaving no file descriptors dangling.
Won't that cause fragmentation? You're forgettng the need to ftruncate or pre-zero the file unless that's been fixed. -- -Alfred Perlstein [[EMAIL PROTECTED]] 'Instead of asking why a piece of software is using "1970s technology," start asking why software is ignoring 30 years of accumulated wisdom.' To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
