On Fri 10-11-23 22:06:22, Charan Teja Kalla wrote: > Thanks Michal!! > > On 11/9/2023 4:03 PM, Michal Hocko wrote: > >> VM system running with ~50MB of memory shown the below stats during OOM > >> kill: > >> Normal free:760kB boost:0kB min:768kB low:960kB high:1152kB > >> reserved_highatomic:0KB managed:49152kB free_pcp:460kB > >> > >> Though in such system state OOM kill is imminent, but the current kill > >> could have been delayed if the pcp is drained as pcp + free is even > >> above the high watermark. > > TBH I am not sure this is really worth it. Does it really reduce the > > risk of the OOM in any practical situation? > > At least in my particular stress test case it just delayed the OOM as i > can see that at the time of OOM kill, there are no free pcp pages. My > understanding of the OOM is that it should be the last resort and only > after doing the enough reclaim retries. CMIW here. Yes it is a last resort but it is a heuristic as well. So the real questoin is whether this makes any practical difference outside of artificial workloads. I do not see anything particularly worrying to drain the pcp cache but it should be noted that this won't be 100% either as racing freeing of memory will end up on pcp lists first. -- Michal Hocko SUSE Labs
