Re: [PATCH 2/2] mm/damon: skip deactivated schemes in watermark checks and add fallback sleep
SJ Park <[email protected]>
| Newsgroups | dev.linux.lists.damon,org.kvack.linux-mm |
|---|---|
| Message-ID | <[email protected]> |
On Sat, 8 Aug 2026 00:18:40 +0800 Liew Rui Yan <[email protected]> wrote: > Hi SJ, > > On Fri, 7 Aug 2026 07:07:39 -0700 SJ Park <[email protected]> wrote: > > > This is an intended implementation. > > > > When all schemes are deactivated by watermarks, DAMON stops monitoring. It was > > implemented in the way because we didn't want DAMON consumes system resource in > > the case. But, later it turned out DAMON's resource consumption is really > > negligible. Rather, it is turned out that it makes DAMON runs with stale > > history when it is activated again. Particularly, regions have 'age' and their > > start/end addresses that was emerged before the deactivation. Those are > > meaningless and could even cause wrong DAMOS decisions. > > > > We don't want that anymore. For a case the user really want DAMON completely > > stops, we introduced 'pause'. For max_nr_snapshot-based deactivation, we don't > > intend to completely stop DAMON. > > > > Maybe the documentation can be updated to further clarify this. > > Thank you for your detailed explanation! I also glad to hear that > DAMON's monitoring's resource consumption is negligible, since I plan to > add a contexts/<N>/always_monitoring parameter later on, allowing users > to decide for themselves whether to keep monitoring even all schemes is > deactivated by watermarks. Unless it is for your real use case, I'd not encourage improving watermarks. Here are contexts. Watermarks was initially developed for DAMON_RECLAIM. But I found it is difficult to be extended for other use cases. Also it has the aobve mentioned problem: losing the monitoring results that was converged over time. I'm planning to develop an alternative superior feature and deprecate watermarks over time. The plan is not having a high priority because I don't show real requirement of that. If anyone wants it for their real use case, please let me know so that I can prioritize. Thanks, SJ [...]