On 10/31/2017 06:15 PM, Vlastimil Babka wrote: > 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... Yeah, makes sense. -- 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>
