On 8/5/19 1:42 AM, Vlastimil Babka wrote: > On 8/3/19 12:39 AM, Mike Kravetz wrote: >> From: Hillf Danton <hdanton@xxxxxxxx> >> >> Address the issue of should_continue_reclaim continuing true too often >> for __GFP_RETRY_MAYFAIL attempts when !nr_reclaimed and nr_scanned. >> This could happen during hugetlb page allocation causing stalls for >> minutes or hours. >> >> We can stop reclaiming pages if compaction reports it can make a progress. >> A code reshuffle is needed to do that. > >> And it has side-effects, however, >> with allocation latencies in other cases but that would come at the cost >> of potential premature reclaim which has consequences of itself. > > Based on Mel's longer explanation, can we clarify the wording here? e.g.: > > There might be side-effect for other high-order allocations that would > potentially benefit from more reclaim before compaction for them to be > faster and less likely to stall, but the consequences of > premature/over-reclaim are considered worse. > >> We can also bail out of reclaiming pages if we know that there are not >> enough inactive lru pages left to satisfy the costly allocation. >> >> We can give up reclaiming pages too if we see dryrun occur, with the >> certainty of plenty of inactive pages. IOW with dryrun detected, we are >> sure we have reclaimed as many pages as we could. >> >> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> >> Cc: Mel Gorman <mgorman@xxxxxxx> >> Cc: Michal Hocko <mhocko@xxxxxxxxxx> >> Cc: Vlastimil Babka <vbabka@xxxxxxx> >> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> >> Signed-off-by: Hillf Danton <hdanton@xxxxxxxx> >> Tested-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx> >> Acked-by: Mel Gorman <mgorman@xxxxxxx> > > Acked-by: Vlastimil Babka <vbabka@xxxxxxx> > I will send some followup cleanup. > > There should be also Mike's SOB? Will do. My apologies, the process of handling patches created by others is new to me. Also, will incorporate Mel's explanation. -- Mike Kravetz
