From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C90B430C631; Fri, 16 Jan 2026 03:18:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768533523; cv=none; b=bZgvieJOXIkyKTWiu34msXsEdqBZpNUwz5Ssz4bmZUEFsCxB+ioLq1dL41LInpev880SrhwPmeoL0AAqpi8aZLqtp+OyZl1WXnm5scv0vOmMo34HLBkhJzzbSUdnnlOkvVfkJ/uKI2OXbC17Ezqk3kmT69CZnNKYd2m2SBAD6xI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768533523; c=relaxed/simple; bh=KEsxUSnwjGF4pQxArZWJG8UMArvuz7FnxwUyaaReGms=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=UEthRKkxb8eDg0fO0Dky+vJpFp7Ge5PHMBODMV8CycZY41bX23AQlmZcteaSHdyNmikXdjU8A+AgHaM6SUYzzNsWM088mq9koA3O1tppXFZ+TRFTru+5ezM/zLdjasoNOelTao3Ua5fdSERSlWETTXqL+wENX40v4FbPjrpadyQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tYWr05Vq; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="tYWr05Vq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4B01CC116D0; Fri, 16 Jan 2026 03:18:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768533523; bh=KEsxUSnwjGF4pQxArZWJG8UMArvuz7FnxwUyaaReGms=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tYWr05VqUGfZCU4UNdsPkbnCkKzql6AFkxRBrIge9Nay2wl9ZhP93gID2fwWkLoxu QC2yQTBVAinsMGdpwouXACSdaPKDDyTyo/HSYnjDe+3LRhj6w7mm8pkdnNEEmSwZLt c9bhJgetOIuabcEBRDd5gSpuYpFrgAbY/FvPCO773e4i+Z3MFnyoryEBUR5tZX3Vn5 Ng8Eo0NnZDYMcxKbnMx19DM1lHhie/UtN152LcesqeQ5KVRFwF2NxdKFw881V+n9q5 V2wzVRiE3vcehY5Wpvs4uQmgJ40wcuBPriuKAymjVGbg4ld1QvA6ymlDXqmwPXG2xT sTHXmU2/WEIMQ== From: SeongJae Park To: JaeJoon Jung Cc: SeongJae Park , damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, rgbi3307@nate.com Subject: Re: [PATCH 1/2] mm/damon/core: modified and tunning damon_split_regions_of() Date: Thu, 15 Jan 2026 19:18:25 -0800 Message-ID: <20260116031826.72372-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: References: Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Thu, 15 Jan 2026 05:18:51 +0900 JaeJoon Jung wrote: > 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. Unfortunately what I asked are still not clearly answered to me. And based on our past conversations including the recent one that I acknowledged as a communication failure [1] and this thread, I expect asking you more questions will not work for me. I don't think that's someone's fault, but obviously that's the current situation. I will not ask you more questions for the reason, unless I get a reason to change my mind. So, to make it crystal clear, for this patch and the one you posted together, Nacked-by: SeongJae Park Thanks, SJ [1] https://lore.kernel.org/20260101224420.73826-1-sj@kernel.org [...]