On Mon, Aug 12, 2013 at 2:54 PM, Nathan Zimmer <nzim...@sgi.com> wrote: > > As far as extra overhead. We incur an extra function call to > ensure_page_is_initialized but that is only really expensive when we find > uninitialized pages, otherwise it is a flag check once every PTRS_PER_PMD. > To get a better feel for this we ran two quick tests.
Sorry for coming into this late and for this last version of the patch, but I have to say that I'd *much* rather see this delayed initialization using another data structure than hooking into the basic page allocation ones.. I understand that you want to do delayed initialization on some TB+ memory machines, but what I don't understand is why it has to be done when the pages have already been added to the memory management free list. Could we not do this much simpler: make the early boot insert the first few gigs of memory (initialized) synchronously into the free lists, and then have a background thread that goes through the rest? That way the MM layer would never see the uninitialized pages. And I bet that *nobody* cares if you "only" have a few gigs of ram during the first few minutes of boot, and you mysteriously end up getting more and more memory for a while until all the RAM has been initialized. IOW, just don't call __free_pages_bootmem() on all the pages al at once. If we have to remove a few __init markers to be able to do some of it later, does anybody really care? I really really dislike this "let's check if memory is initialized at runtime" approach. Linus -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/