On 1/25/2021 4:24 AM, David Rientjes wrote: > On Wed, 20 Jan 2021, Vlastimil Babka wrote: > >> On 1/19/21 8:26 PM, David Rientjes wrote: >>> On Mon, 18 Jan 2021, Charan Teja Reddy wrote: >>> >>>> should_proactive_compact_node() returns true when sum of the >>>> weighted fragmentation score of all the zones in the node is greater >>>> than the wmark_high of compaction, which then triggers the proactive >>>> compaction that operates on the individual zones of the node. But >>>> proactive compaction runs on the zone only when its weighted >>>> fragmentation score is greater than wmark_low(=wmark_high - 10). >>>> >>>> This means that the sum of the weighted fragmentation scores of all the >>>> zones can exceed the wmark_high but individual weighted fragmentation >>>> zone scores can still be less than wmark_low which makes the unnecessary >>>> trigger of the proactive compaction only to return doing nothing. >>>> >>>> Issue with the return of proactive compaction with out even trying is >>>> its deferral. It is simply deferred for 1 << COMPACT_MAX_DEFER_SHIFT if >>>> the scores across the proactive compaction is same, thinking that >>>> compaction didn't make any progress but in reality it didn't even try. >>> >>> Isn't this an issue in deferred compaction as well? It seems like >>> deferred compaction should check that work was actually performed before >>> deferring subsequent calls to compaction. >> >> Direct compaction does, proactive not. >> >>> In other words, I don't believe deferred compaction is intended to avoid >>> checks to determine if compaction is worth it; it should only defer >>> *additional* work that was not productive. >> >> Yeah, that should be more optimal. >> > > Charan, is this something you'd like to follow up on, or should I take a > look instead? > Sure David. Happy to follow up on this. Thanks! > Thanks! > -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
