On Mon, 10 Sep 2012 13:55:15 +0200 Michal Hocko <mhocko@xxxxxxx> wrote: > > >OK. Thanks for the clarification. The main question remains, though. Is > > >this worth for memblock_is_memory? > > > > There are many call sites need to call pfn_valid, how can you guarantee all > > the addrs are between memblock_start_of_DRAM() and memblock_end_of_DRAM(), > > if not can this reduce possible overhead ? > > That was my question. I hoped for an answer in the patch description. I > am really not familiar with unicore32 which is the only user now. > > > I add unlikely which means that this will not happen frequently. :-) > > unlikely doesn't help much in this case. You would be doing the test for > every pfn_valid invocation anyway. So the main question is. Do you want > to optimize for something that doesn't happen often when it adds a cost > (not a big one but still) for the more probable cases? > I would say yes if we clearly see that the exceptional case really pays > off. Nothing in the changelog convinces me about that. I don't believe Michal's questions have been resolved yet, so I'll keep this patch on hold for now. -- 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>