在 2020/11/25 下午11:38, Vlastimil Babka 写道: > On 11/20/20 9:27 AM, Alex Shi wrote: >> The current relock logical will change lru_lock when found a new >> lruvec, so if 2 memcgs are reading file or alloc page at same time, >> they could hold the lru_lock alternately, and wait for each other for >> fairness attribute of ticket spin lock. >> >> This patch will sort that all lru_locks and only hold them once in >> above scenario. That could reduce fairness waiting for lock reget. >> Than, vm-scalability/case-lru-file-readtwice could get ~5% performance >> gain on my 2P*20core*HT machine. > > Hm, once you sort the pages like this, it's a shame not to splice them instead of more list_del() + list_add() iterations. update_lru_size() could be also called once? Yes, looks it's a good idea to use splice instead of list_del/add, but pages may on different lru list in a same lruvec, and also may come from different zones. That could involve 5 cycles for different lists, and more for zones... I give up the try.
