On Thu, 17 Mar 2011 15:40:26 +1030 Christopher Yeoh <cyeoh@xxxxxxxxxxx> wrote: > > Thinking out loud: if we had a way in which a process can add and > > remove a local anonymous page into pagecache then other processes > > could access that page via mmap. If both processes map the file with > > a nonlinear vma they they can happily sit there flipping pages into > > and out of the shared mmap at arbitrary file offsets. The details > > might get hairy ;) We wouldn't want all the regular mmap semantics of > > Yea, its the complexity of trying to do it that way that eventually lead me > to implementing it via a syscall and get_user_pages instead, trying to > keep things as simple as possible. The pagecache trick potentially gives zero-copy access, whereas the proposed code is single-copy. Although the expected benefits of that may not be so great due to TLB manipulation overheads. I worry that one day someone will come along and implement the pagecache trick, then we're stuck with obsolete code which we have to maintain for ever. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>