On Tuesday, 4 of November 2008, Dave Hansen wrote: > On Tue, 2008-11-04 at 09:54 +0100, Rafael J. Wysocki wrote: > > To handle this, I need to know two things: > > 1) what changes of the zones are possible due to memory hotplugging > > (i.e. can they grow, shring, change boundaries etc.) > > All of the above. OK If I allocate a page frame corresponding to specific pfn, is it guaranteed to be associated with the same pfn in future? > > 2) what kind of locking is needed to prevent zones from changing. > > The amount of locking is pretty minimal. We depend on some locking in > sysfs to keep two attempts to online from stepping on the other. > > There is the zone_span_seq*() set of functions. These are used pretty > sparsely, but we do use them in page_outside_zone_boundaries() to notice > when a zone is resized. > > There are also the pgdat_resize*() locks. Those are more for internal > use guarding the sparsemem structures and so forth. > > Could you describe a little more why you need to lock down zone > resizing? Do you *really* mean zones, or do you mean "the set of memory > on the system"? The latter, but our internal data structures are designed with zones in mind. > Why walk zones instead of pgdats? This is a historical thing rather than anything else. I think we could switch to pgdats, but that would require a code rewrite that's likely to introduce bugs, while our image-creating code is really well tested and doesn't change very often. Thanks, Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
