On Mon, Feb 21, 2005 at 01:29:41AM -0600, Ray Bryant wrote: > This is different than your reply above, which seems to imply that: > > (A) Step 1 is to migrate mapped files using mbind(). I don't understand > how to do this in general, because: > (a) I don't know how to make a non-racy list of the mapped files to > migrate without assuming that the process to be migrated is > stopped
That was just a stop gap way to do the migration before you have xattrs for shared libraries. If you have them it's not needed. > and (b) If the mapped file is associated with the DEFAULT memory policy, > and page placement was done by first touch, then it is not clear > how to use mbind() to cause the pages to be migrated, and still > end up with the identical topological placement of pages after > the migration. It can be done, but it's ugly. But it really was only intended for the shared libraries. > (B) Step 2 is to use page_migrate() to migrate just the anonymous pages. > I don't like the restriction of this to just anonymous pages. That would be only in this scenario; I agree it doesn't make sense to add it as a general restriction to the syscall. > > Fundamentally, I don't see why (A) is much different from allowing one > process to manipulate the physical storage for another process. It's > just stated in terms of mmap'd objects instead of pid's. So I don't > see why that is fundamentally different from a page_migration() call > with va_start and va_end arguments. An mmaped object exists on its own. It's access is fully reference counted etc. > The only problem I see with that is the following: Suppose that a user > wants to migrate a portion of their own address space that is composed > of (at last partly) anonymous pages or pages mapped to a file associated > with the DEFAULT memory policy, and we want the pages to be toplogically > allocated the same way after the migration as they were before the > migration? It doesn't seem very realistic to me. When a user wants to change its own address room then they can use mbind() from the beginning and they should know how their memory layout is. -Andi - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
