On Friday, 27 April 2007 06:52, Pekka J Enberg wrote: > On Thu, 2007-04-26 at 09:56 -0700, Linus Torvalds wrote: > > > which will map in the snapshot, return the mapped address and the size > > > (and if you want to support snapshots > 4GB, be my guest, but I > > > suspect > > > you're actually *better* off just admitting that if you cannot shrink > > > the snapshot to less than 32 bits, it's not worth doing) > > On Fri, 27 Apr 2007, Nigel Cunningham wrote: > > That inherently limits the image to half of available ram (you need > > somewhere to store the snapshot), so you won't get the full image you > > express interest in below. > > It doesn't. We can make the userspace mapped pages copy-on-write. As long > as the userspace makes sure there's not much activity during > snapshot/shutdown, we will be fine. What we probably do need to copy is > kernel pages.
The user space is (and IMHO should be) frozen way before that and what you're suggesting here is what I wanted to implement some time ago. The problem with this was that the user space pages may be updated, for example, by device drivers as a result of some deferred I/O after we've snapshotted the system. I didn't know how to find out which pages owned by the user space could be updated this way, so I gave up at that time. Greetings, Rafael - 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/