On Saturday, 14 April 2007 01:03, Nigel Cunningham wrote: > Hi. > > On Sat, 2007-04-14 at 00:57 +0200, Rafael J. Wysocki wrote: > > > > > Well, I'm not sure. First, we don't really know what the value of it should be > > > > > and this alone is a good enough reason for making it tunable, IMHO. Second, I > > > > > think different systems may need different PAGES_FOR_IO and taking just the > > > > > maximum (even if we learn how much that actually is) seems to be wasteful in > > > > > > > > Well, it is wasteful as in "we save slightly smaller image than we > > > > could". That's okay with me. > > > > > > No. If the driver can't allocate the memory, your call to device_suspend > > > will fail. This isn't about image size but about success or failure to > > > hibernate. > > > > If we take PAGES_FOR_IO to be the maximum over all possible configurations > > that can hibernate, the majority of systems will just create smaller images than > > they could have created for smaller PAGES_FOR_IO, but all of them will be > > able to hibernate. :-) > > You also use PAGES_FOR_IO in enough_free_mem. Say you set it to the 9000 > pages I mentioned before (35M). On a machine with 64 megabytes of > memory, you'll never be able to suspend because you'll never satisfy > > free > nr_pages + PAGES_FOR_IO + meta Well, in fact our tunable would need to be independent of PAGES_FOR_IO so that the memory shrinker could free some spare memory for the drivers. > I'll freely admit that 64 megabytes is tiny nowadays, but it's not > completely unknown. The point is really that you're effectively making > swsusp unusable for machines with RAM < (PAGES_FOR_IO * (say) 3). But > what do you set PAGES_FOR_IO to? There'll always be someone with > $WHIZ_BANG_CONFIG who is pushing to have the value increased, and every > increase knocks out more of your lowend users. Yes, that's why I said I wasn't sure whether or not the additional tunable was needed. Still, with the notifiers we have a chance to handle the problem automatically and the tunable would require the user to set the right value. Greetings, Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
