On 2017/6/7 10:53, Minchan Kim wrote: > Hi, > > On Tue, Jun 06, 2017 at 09:00:55PM +0800, zhong jiang wrote: >> On 2017/1/31 7:40, Minchan Kim wrote: >>> Hi Vinayak, >>> Sorry for late response. It was Lunar New Year holidays. >>> >>> On Fri, Jan 27, 2017 at 01:43:23PM +0530, vinayak menon wrote: >>>>> Thanks for the explain. However, such case can happen with THP page >>>>> as well as slab. In case of THP page, nr_scanned is 1 but nr_reclaimed >>>>> could be 512 so I think vmpressure should have a logic to prevent undeflow >>>>> regardless of slab shrinking. >>>>> >>>> I see. Going to send a vmpressure fix. But, wouldn't the THP case >>>> result in incorrect >>>> vmpressure reporting even if we fix the vmpressure underflow problem ? >>> If a THP page is reclaimed, it reports lower pressure due to bigger >>> reclaim ratio(ie, reclaimed/scanned) compared to normal pages but >>> it's not a problem, is it? Because VM reclaimed more memory than >>> expected so memory pressure isn't severe now. >> Hi, Minchan >> >> THP lru page is reclaimed, reclaim ratio bigger make sense. but I read the >> code, I found >> THP is split to normal pages and loop again. reclaimed pages should not >> be bigger >> than nr_scan. because of each loop will increase nr_scan counter. >> >> It is likely I miss something. you can point out the point please. > You are absolutely right. > > I got confused by nr_scanned from isolate_lru_pages and sc->nr_scanned > from shrink_page_list. > > Thanks. > > > . > Hi, Minchan
I will send the revert patch shortly. how do you think? Thanks zhongjiang
