Hello, Christoph. On Tue, Jun 17, 2014 at 02:42:48PM -0500, Christoph Lameter wrote: > > > I much prefer the model where the thing that -published- the pointer is > > > responsible for memory ordering. After all, if a task allocates some > > > zeroed memory, uses it locally, then frees it, there is no ordering > > > to worry about in the first place. The memory allocator doing the > > > initialization cannot tell how the memory is to be used, after all. > > > > Yeah, "publish" is a nice verb to put on it. No objection. > > Well that "publishing" of the structure that contains the per cpu offset > is actually what most of the current code does. So we do not need any > additional synchronization. Clarifying the responsibility for > synchronization being with the code which does the alloc_percpu would be > good.
Sure, we can declare that it follows the same rules as normal memory allocations - that is, the zeroing belongs to the allocating cpu and propagation is fully the responsbility of users including data dep barrier when necessary. It seems a lot more confusing to me than normal memory allocations mostly because the ownership isn't immediately clear; however, it could be that we just need to clarify. I'll think more about it. Thanks. -- tejun -- 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/
