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b=hK3X0I0Lmube4dVvbjOzqRQOzBfAEW9WHlkZLcjYRD2dhvBbrYtZduvYQ8nfZx2Hg X8grAnmwfrylot6YmXa/uWBvGfeYuiQM2RHKRHxAR/jVTX5UgUsJnRsfymc0jLyW39 Z/SILDyUmSiGmFuz6D6qmU/rlNfEUq9HQO82r1KAGAGKThPh5pZtF2WFhpJHpjOENZ oPcCDWIm4PV/fokbtnO2SCvkTqwnMJ5SnGm3fxJHy5hnKC7ySznb2sobwO9eqf2I3f EbGc/08iMXnzZxFwzuTXLaW4thauo3Gzwh3fqS3Ido0zaGaozJ8EEoO2tbJw8+iSH9 NpfG15+ULe4wg== From: SJ Park To: Liew Rui Yan Cc: SJ Park , damon@lists.linux.dev, linux-mm@kvack.org Subject: Re: [RFC/Discussion] mm/damon: Implementation for paused kdamond Date: Mon, 14 Sep 2026 17:28:35 -0700 Message-ID: <20260915002836.101895-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260914153640.8481-1-aethernet65535@gmail.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: a15qxhqe5iux7ptupcqcjt5jmoig3xts X-Rspamd-Queue-Id: A077FC0006 X-Rspamd-Server: rspam07 X-HE-Tag: 1789432124-742378 X-HE-Meta: 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 ZSesXBAF AYoURuzKdEC5lgzjjRKlIX9yQnl0VZUTgH3XKuRHYjnt2VFBwQCBJdKzfGUVvLLmi5QkorLjW6I4DBXp1f4wKTde1kRjYD9A1dG+9p41i7byY6zExYbWWXm0vqLtx6rQtvUYnJDBY8dxWjy1lg9xYf/PWgtmZ+A6TWZMx3YuTadCTlp/6pnCj9UF7RjBk37jKQuuMxLX5xOFWlC7dXCoau65vQatFPhhFiSYDScaZZbmle8r/gfGl7sdW6ASWDVcIJb/A Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 14 Sep 2026 23:35:10 +0800 Liew Rui Yan wrote: > Hi SJ, > > I noticed that the current implementation for paused kdamond is > periodically applies online parameter updates by kdamond_usleep(). > > I'd like to know if we should change it to waitqueue to achieve a lower > power consumption? I'd like to make a data driven decision :) > > Previous Discussion > =================== > > I noticed that when you introduced ctx->pause [1], Sashiko asked the > same question, and your response at the time was: > > "sample internval is 5ms by default and recommended auto-tuning > setup makes it hundreds of milliseconds. So I don't think such > change is required." > > I'm curious that, did you think it wasn't neccessary to change it to > waitqueue when it was introduced, or it wasn't neccessary to do so even > after it had been introduced? I guess I thought so when the quiestion is raised. > > Asussmption > =========== > > This is just my assumption, not a real use case I knew: When 'pause' is > set on an Android device, user might want DAMON to stop running > completely when the screen is off, thereby reducing the load on the CPU > without losing important information such as regions and age. > > The current polling may make it harder for the phone to enter idle mode, > resulting in some unnecessary power consumption. > > However, pause feature is only present in the stable version v7.2 or > higher, and since the latest Android kernel is 6.18, this highly > unlikely will affect any Android users. If whoever comes with a data that require changes, we can discuss. > > [1] https://lore.kernel.org/damon/20260321202858.98091-1-sj@kernel.org Thanks, SJ [...]