On Sun, 12 Sep 2021 19:54:47 +0800 Yongmei Xie <yongmeixie@xxxxxxxxxxx> wrote: > The current implementation count all the pages which have shadow entry in radix tree as > the event of refault (page or anon). That means all the pages which have ever been > cached in lru are counted as refault. But I think it's not 100% percent correct. > > Because usually inode has much longer life cycle than the pages belonging to it. > So if the inode was accessed from time to time, then it won't be reclaimed unless much > severe memory pressure happens. > > Then if page was reclaimed several days ago, when it's accessed again, it will be marked as > refault event. Then page was reclaimed an hour ago, when it's accessed again, it will be > marked as refault event as well. From the refault metric alone, I cannot tell whether the > previous reclaim process has evicted some useful pages. That makes things worse in situation > of proactive reclaim. We's like to known whehter the previous policy reclaim too much > meaningful data other than working set transition. So we'd like see the refault rate, but it > includes all the historical reclaim. > > >From my point of view, if the refaut distance is larger than file cache size, we don't > have to count it refault at all. Because it's too long to be memorized down. Thanks. Do you have any runtime testing results which demonstrate a benefit?
