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Wed, 14 Jan 2026 12:19:02 -0800 (PST) MIME-Version: 1.0 References: <20260113121646.31441-1-rgbi3307@gmail.com> <20260114154622.100466-1-sj@kernel.org> In-Reply-To: <20260114154622.100466-1-sj@kernel.org> From: JaeJoon Jung Date: Thu, 15 Jan 2026 05:18:51 +0900 X-Gm-Features: AZwV_QgIjApPfUqHCJ9CXsY1zOWH5eS4Wjd7hCBP9UHgwERtGc2_9jqPezDh2rg Message-ID: Subject: Re: [PATCH 1/2] mm/damon/core: modified and tunning damon_split_regions_of() To: SeongJae Park Cc: damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, rgbi3307@nate.com Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: 7t1jgrbwqun65k616fg4gmwzm8ffecqz X-Rspam-User: X-Rspamd-Queue-Id: 0E0764000A X-Rspamd-Server: rspam08 X-HE-Tag: 1768421943-438746 X-HE-Meta: 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 f4lnIQst hkfQl9fy7z4+MwiPNxmQWKvQQeB9EsO2WfJGD0ADMW9vlH3wS08cNLsjdl7xNQOzyPU893YxYq7PtoN8lal32MP0iVrYK9QAGx6RBouGtllfQ1P25cDpAt0lDYy1NsSnUTfCzmm27MR06i0slUKhZORUUGtIgpaClcce8lfA21OL4ygKYea23YNDjfT28ysO4YTIZTA+txN8L0PBznbzCJjmnBCI3GVkVdR3ru9gg///8nZgVRupumLleDt6k/T/lLxqZQXc4OKBpw5Gapnwapy2apEAQtKrpYK7RMeFUGPbgKwleqrLU2Bh4VEBjz2LXrr1txH7KUE1Liej/e6K0w4c/JFvX7MOZMtsjbJOA4maPhsNmtEl2gMSw1efySF4nszghT9jnGh+h7z/8oRbXRgY46DjMZQkeu+NxXY4T5fDYqMDW2PwjQ6YGN4L2ROWdNl5n X-Bogosity: Ham, tests=bogofilter, spamicity=0.176332, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 15 Jan 2026 at 00:46, SeongJae Park wrote: > > Hello JaeJoon, thank you for continued interest in DAMON. > > On Tue, 13 Jan 2026 21:16:42 +0900 JaeJoon Jung wrote: > > > Before modification: > > sz_region > > |--------|--------|--------||--------|--------|--------|--------| > > nr_subs: 1 2 3 4 5 9 > > split random: <----------- (*] randmon LOST --------------> > > > > When dividing sz_region at rand, the random value may be small, such as > > 1 or 2. At this time, there is a problem that only the front areas > > corresponding to 1 and 2 are divided, and the remaining back area > > becomes too wide. If the area is too wide, there will be many missed > > address access judgments. > > > > After modification: > > sz_region > > |--------|--------|--------|--------|--------|--------|--------|| > > nr_subs: 1 2 3 4 5 9 > > split from <------------ (sz_region / nr_subs) ------------------> > > > > It is recommended to divide sz_region evenly in the ratio (sz_region / > > nr_subs) rather than using rand. In this way, if you decide nr_subs well, > > you can logically match the number of divisions and their sizes. > > I was thinking about how to reply to this patch. Since it is taking unusually > long time, let me add short comments for direct future of this patch. After much thought, you ask a simple question below. > > The existing code uses random() for a reason. This change might break it. Can > you further explain what was the point of the use of random(), and why this > change is not breaking it? To find a needle in a haystack, is it right to keep poking around randomly? > > > > > Signed-off-by: JaeJoon Jung > > Unless you can give me a convincing answer to my above question, > > Nacked-by: SeongJae Park > > Same for your followup patch [1]. Btw, please send patches of same series as > one thread from next time. I sent you two after much deliberation so that you can see them clearly. Thanks, JaeJoon > > [1] https://lore.kernel.org/20260113121731.31468-1-rgbi3307@gmail.com > > > Thanks, > SJ > > [...]