On Tue, 2012-12-04 at 16:24 -0800, Andrew Morton wrote: > On Tue, 04 Dec 2012 18:17:08 -0600 > Matt Mackall <mpm@xxxxxxxxxxx> wrote: > > > On Tue, 2012-12-04 at 15:21 -0800, Andrew Morton wrote: > > > On Tue, 04 Dec 2012 09:15:10 +0400 > > > Pavel Emelyanov <xemul@xxxxxxxxxxxxx> wrote: > > > > > > > > > > > > Two alternatives come to mind: > > > > > > > > > > 1) Use /proc/pid/pagemap (Documentation/vm/pagemap.txt) in some > > > > > fashion to determine which pages have been touched. > > > > [momentarily coming out of kernel retirement for old man rant] > > > > This is a popular interface anti-pattern. > > > > You shouldn't use an interface that gives you huge amount of STATE to > > detect small amounts of CHANGE via manual differentiation. > > I'm not sure that's what checkpoint-restart will be doing. If we want > to determine "which pages have been touched since the last checkpoint > ten minutes ago" then that set of touched pages *is* state. And it's > not "small"! Yeah, there is definitely a middle-ground here between "I want high-frequency updates" and "I want to see the whole picture". The filesystem analogy is backups: we don't have any good way to say "find me all files changed since yesterday" short of "find all files". The closest thing is explicit snapshotting. -- Mathematics is the supreme nostalgia of our time. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>