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bh=e3daVw9VGOXj3R/V1W0E5XdXB4FzvZf9+xPmzhbSgJM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Q6P9ffV6a8+xy8VK8inrRcDrU7sh4cLGHJvj3DBzBzEJi/Phxuq4GeIEFYfyLR7eJ EoN/NNte+BRjkWbshztJPm0ed10d0ju1uKqJWadfmwcSUF/oI0TnvNxOioz2qJRHhX 1TZ7NcpGWRX4YcKpM8BmgtlMl1qJ1FZkPyivLc0e4ow9zkGYPiF/+VuWDsqr0Dnupo n/23pLs+Be6vFqYX/RZpCzyicUfRbvoqsLokfEXG0704DNcEj6NbPLW1wZDkpGmq18 gKVDeGn4aqiVkO+FA9mfz5mB1k/QmpLc1g9Mj365pAWUrIeR5dCGsVpwi5yJo7tBuJ csi7m+gdtGEYA== From: SeongJae Park To: Sang-Heon Jeon Cc: SeongJae Park , honggyu.kim@sk.com, damon@lists.linux.dev, linux-mm@kvack.org Subject: Re: [PATCH] mm/damon/core: set initial quota->charged_from to INITIAL_JIFFIES Date: Mon, 18 Aug 2025 16:01:45 -0700 Message-Id: <20250818230145.4056-1-sj@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250818183803.1450539-1-ekffu200098@gmail.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 0D8662001A X-Stat-Signature: aea41rcykmx87y5w9ed573j5zwf8us6t X-Rspam-User: X-HE-Tag: 1755558108-713609 X-HE-Meta: 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 4bIeF9qi SXGCwiA4JE1k4xd0IOe3gEUaL9GNro1lsasXt3TuirZXEJeML3M/XNRkVuQErhpgrSzA7axJWfm71vJxM6igXB5C/Ek3Co8qdz1wLzGgvDjIR/y9WUSwpA7GZNFEchnGoJM4A8zMtqwZ9WQ8kgE4kbnIykrhnrRxzhVr4VGLsNrScmGmS5G2ftcw+hh76EqMD9yrIzpZJhoFFb8VgHwI74Wq6x+mynWLPLqiIjo0Ocht9xh7O8FB/AI9p9lvG5Hdl3rUF7EX1tLz7BV4j7GfJnu0t8A== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hello Sang-Heon, On Tue, 19 Aug 2025 03:38:03 +0900 Sang-Heon Jeon wrote: > Kernel initialize "jiffies" timer as 5 minutes below zero, as shown in > include/linux/jiffies.h > > /* > * Have the 32 bit jiffies value wrap 5 minutes after boot > * so jiffies wrap bugs show up earlier. > */ > #define INITIAL_JIFFIES ((unsigned long)(unsigned int) (-300*HZ)) > > In 32bit system, if quota->charged_from is initialized to 0 as it now, > it will not adjust event if reset_interval_ms passes for the first 5 > minutes. jiffies is unsigned. Hence the initial invocation of time_after_eq() in damos_adjust_quota(), which is the only place reading quota->charged_from, will return 'true' and the quota adjustment would be done without delay, unless the scheme apply interval is unrealistically big. Please let me know if I'm missing something. Thanks, SJ [...]