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b=YPHVB+RsV8E8ByYQeqKs4psTqgiGZJiFaUvXjDZL7W756Idf++GXwTy+3W8SIaJ6Z u/baU/vgMOYHfRXSBKOmKjB0V13msSrC0CXt0D/42iHr7kQICeXkzbEJ1961TAbnID jE1rtTqqbLe6cj9oGheVGP9DxxskWP8qAC9Zby1sq7/+s7XqLasthNJIJ7ge8I1jLo VZQHd1Jqv+/uNTqgPCTT6qlYxG1bXOC+9Izg6XWI7Zgd83d6gF3lIZQR8zkM6qMfiU u79ZMfCFqU0QiT6uAeci3EDxjdw3rfy7Gs5SbzorzCBKOsCtj/R65v3S/8wmo01ReX vrqk1EvQAoe4A== From: SJ Park To: Liew Rui Yan Cc: SJ Park , damon@lists.linux.dev, linux-mm@kvack.org Subject: Re: [PATCH 2/2] mm/damon: skip deactivated schemes in watermark checks and add fallback sleep Date: Sat, 8 Aug 2026 15:50:53 -0700 Message-ID: <20260808225053.111143-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260808215554.6045-1-aethernet65535@gmail.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 7B4AD140004 X-Stat-Signature: nee3w5kfbmzao3ubrd5ckz9kjjatjrug X-HE-Tag: 1786229463-568642 X-HE-Meta: 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 TcklwNot p7kZDDPCc+QIi8D3LxSRqtLB6GNwqXhskuDx+djEEJNprguH7kernUMQhyuNKuXcFR2mNCRxM8iQzBHd1lBI74aegPZrQqB3UwCN2HV6RPWusEhTRCBUYJGubcN4tBLRfymOUqGzMAvVhFEEinhb8rir2zBca55wAePDA59RanKWMqFnomkoaNHPtDuxFPZKtBu6O/eJ3x3JbbJRq9/JvzTsuKEZew4nX5iz1UCspKatLOZssbP/DhH5w0KXp8Satffhd Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, 9 Aug 2026 05:55:54 +0800 Liew Rui Yan wrote: > Hi SJ, > > On Fri, 7 Aug 2026 07:07:39 -0700 SJ Park 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. > > Wait, according to the documentation and the code, DAMON will still stop > monitoring when all schemes is deactivated. That's correct. [...] > Should this be changed to monitoring will not stop? No. The change you mentioning will be unexpected behavioral change. > > Also this patch (0002) add a new function named damos_is_deactivated(), > it checks both wmarks.activated and max_nr_snapshot conditions, and I > replace the wmarks.activated-only with this new function. Let's distinguish watermarks based deactivation and max_nr_snapshots based deactivation. They are completely different things and have different behaviors. The current documentation may confused you. > > I am sorry if my commit message has caused you any misunderstanding. No worry. The current poor documentation is the one to blame in my opinion. Thanks, SJ [...]