On 10/19/2017 05:33 PM, Michal Hocko wrote: > On Thu 19-10-17 20:26:57, Anshuman Khandual wrote: >> Its already assumed that the PageActive flag is clear on the input >> page, hence page_lru(page) will pick the base LRU for the page. In >> the same way page_lru(page) will pick active base LRU, once the >> flag PageActive is set on the page. This change of LRU list should >> happen implicitly through the page flags instead of being hard >> coded. > > The patch description tells what but it doesn't explain _why_? Does the > resulting code is better, more optimized or is this a pure readability > thing? > > All I can see is that page_lru is more complex and a large part of it > can be optimized away which has been done manually here. I suspect the > compiler can deduce the same thing. We shouldn't overestimate the compiler (or the objective conditions it has) for optimizing stuff away: After applying the patch: ./scripts/bloat-o-meter swap_before.o mm/swap.o add/remove: 0/0 grow/shrink: 1/0 up/down: 160/0 (160) function old new delta __activate_page 708 868 +160 Total: Before=13538, After=13698, chg +1.18% I don't think we want that, it's not exactly a cold code... -- 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>
