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Thu, 17 Sep 2026 11:00:19 -0700 (PDT) Received: from LAPTOP-97G9G880.domain.name ([106.222.202.182]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-33bf5b1d335sm18580264eec.28.2026.09.17.11.00.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Sep 2026 11:00:19 -0700 (PDT) From: Karthikeyan KS To: Sang-Heon Jeon Cc: SJ Park , Andrew Morton , damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/damon: reject zero sampling interval Date: Thu, 17 Sep 2026 18:00:13 +0000 Message-ID: <20260917180013.1279018-1-karthiproffesional@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: ADFDFA000C X-Rspam-User: X-Stat-Signature: 4bd5xc9zhcuzbu341ae8zjjt9nu1pwoe X-HE-Tag: 1789668021-656146 X-HE-Meta: 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 +Gx5zO1E aWkrDX3HJoA1JyKEW88yFJIGv5xAHy7PVZet5bIea1WUdowrXOiX6m4D04YsqO+9OnFufDw4x8JAbpgaG8eBgsDGVUBtq1AxCzmZAfh1qd8vNSdUtx5Pe2cPt/yPyLrO7E8SK5guAk1qX4grwgZ54nHugGCE5L/Jy4DdwlOhVYSZktJdUIAIYi5EU2HFhL2EplD03oxc+qcZowXjqtX9z+1nLGhAnbHKSVs40FUSSYLwl+ODl+8d2BSZjWgREqhaR352yO7J9HKkqVXGAAG+yRRocv6cgkHxBHjCEBIIYqGZTSjvPpDzZci81Qpbs5pfPPDimCkMKPtARjovxFq+zcsF6wWvGGXBiUnt+ls/4LWbH6Kqwdiim9/lOgFz9x/lLFriinZ2uVxkdgrLy8G2DSHpgzJTDt4q+EkiJeiq8+e5A7S0je/AxDS614Q== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Sang-Heon, Hi SJ, > I think SJ already commented on a similar patch. please refer to [1] > > [1] https://lore.kernel.org/all/20260722094304.3132750-1-dayou5941@163.com/ Thanks, missed that thread. Same objection applies to mine. > Can't we keep supporting zero sample interval and fix the warning > or the real bug instead? I measured a few floors for kdamond_usleep(): floor kdamond CPU (3s) vs sample_us=5000 1us 84% 28x 100us 42% 14x 1000us 12% ~3x 5000us ~2% 1x (matches control) 5000us is damon_new_ctx()'s own default, and at that floor the spin is just gone. Would you rather we just document sample_us=0 as accepted/expected behavior, or clamp it to that default inside damon_set_attrs()? Thanks, Karthikeyan KS