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b=b8RNwxrCoval3cj7VaO5A2ekKiYwrG6m4fB1V1beYqHCJFlZdt063QAGd6toVBr83 etntU9CFZEUgPMcYVHZYJ3UhlXaIH0XTgMdZnJP+k/BDfMMK/VhvuOaAwCV+zDwBLQ ml2wpf8Zr6aaSjwttXo5aCMFtc6+9ht+prziUkDAvgsllki2tEiwMc0LOrxnsO/Yrx /HczPATqi9To/i5RdnbPeA9DVAEBjTllfSyTjBI01XNDiQrtCIs1Im5iCgvxW/YBVZ dfAhqJfxR9HrEqTQPEq28TlwGujAWv+9D0qI/gethfpu71Tb08V2WRj6J2l/Xg+wa5 qJQPkO9w8jPMA== From: SJ Park To: "Adrian Huang (Lenovo)" Cc: SJ Park , Andrew Morton , damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, ahuang12@lenovo.com Subject: Re: [PATCH 1/1] mm/damon/core: simplify minimum watermark wait time calculation Date: Tue, 10 Nov 2026 07:39:06 -0800 Message-ID: <20261110153907.158338-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20261110085132.1023-1-adrianhuang0701@gmail.com> References: X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: A0B0312000F X-Stat-Signature: 6565owyyb8ecaztqtoq1bb4bfobwyngb X-Rspam-User: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-HE-Tag: 1794325160-595236 X-HE-Meta: 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 YxSNx3Qf eO5Wxh36qD4gUIkDmw8lHhFZvNaeUuLCw4VBPqR2NFLPJjGg80LGO+QdKGb/ZKpoaMG10d+9cVaONyi3XJ1sr3MSknXaw+mwD9rqSSv/1bs5JZ3ja+idvuaVsuyqELi5VDTGfxHTVkfR/iSiavxOwx7FaGPBypqq7W1cS6u3KL2w7LGrd9d4cPnxGWOVENEnL1v0j13uBhCY/ccBmwoQ7DA0sfE+psNvVRLTidCBUQzutdTddDQUjaFQnts1bZApHV1l2zbaDpgL2Wc0= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 Hello Adrian, On Tue, 10 Nov 2026 16:51:32 +0800 "Adrian Huang (Lenovo)" wrote: > The minimum watermark wait time calculation uses an additional boolean > variable, init_wait_time, to determine whether min_wait_time has been > initialized. > > Simplify the logic by using list_is_first() to identify the first > scheme and initialize min_wait_time accordingly. Subsequent schemes > update min_wait_time only when their waiting intervals are shorter. > > This removes the unnecessary boolean variable while preserving the > existing behavior, including the case where no schemes are configured. > > Signed-off-by: Adrian Huang (Lenovo) > --- > mm/damon/core.c | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/mm/damon/core.c b/mm/damon/core.c > index d36823f4d092..93ec684a113c 100644 > --- a/mm/damon/core.c > +++ b/mm/damon/core.c > @@ -3985,14 +3985,12 @@ static int kdamond_wait_activation(struct damon_ctx *ctx) > > while (!kdamond_need_stop(ctx)) { > unsigned long min_wait_time = 0; > - bool init_wait_time = false; > > damon_for_each_scheme(s, ctx) { > wait_time = damos_wmark_wait_us(s); > - if (!init_wait_time || wait_time < min_wait_time) { > - init_wait_time = true; > + if (list_is_first(&s->list, &ctx->schemes) || > + wait_time < min_wait_time) > min_wait_time = wait_time; > - } I implemented and used list handling wrappers like damon_for_each_scheme(), to hide implementation details of data structures. This change exposes some of such details. If we agree we have to remove init_wait_time, I'd prefer adding a sort of damon_first_scheme() like wrapper. But, init_wait_time really need to be removed? I cannot show clear benefit of removing it that justifies adding a new wrapper. To someone or on some evironments, init_wait_time might making the code too difficult to read or inefficient (system having so small amount of memory?), though. If not, I'd suggest dropping this. What do you think, Adrian? Thanks, SJ [...]