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 B04CF3EBF2F for ; Tue, 17 Feb 2026 00:13:30 +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=1771287210; cv=none; b=DF9XLYESnPTR2KFGKqlu9xXdeX/emnd+m26d1uxTEgtx5B32bIJ4QeJd+2Z+b/zybGu8q+2vPNW1DDBzw/jzEQTlK2hr5aa5VSw5P7mt1gtrUhJqBBxssBZIoc+TVVtcSO9ahNElBjqcCP+ATk9ofSdbyNno41JWwn0oe/u/+8Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771287210; c=relaxed/simple; bh=ip/RBWDdw9HJHNpuhUYZixgSxIZwtTtHs1lSkKTGCYA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=QX25aOfpehYY47x0vnFeFXt0wb0oG/oUooA0E4Vsfc/DOKLxRxEkJEnQDDxRyAgDbg5sR7xEL7X1JjXUfmLQDBKBdYzZ1smZK87I32nqLYy2V8TsPp5AnnQl3AOKiE81CZbDTTx6Rn5cJOplT+V11knt1xJZFmmizAz/ijfcsRU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=q3HvoVkb; 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="q3HvoVkb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2F1F0C116C6; Tue, 17 Feb 2026 00:13:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771287210; bh=ip/RBWDdw9HJHNpuhUYZixgSxIZwtTtHs1lSkKTGCYA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=q3HvoVkbCc27zBuAZ4eYMvvr/Ika5mjCjEHP7Tsr5LQ1pMKd4Gyh3kbHLUJMcrpsY oYpSjtveXgfEaNKPIVPJziFXuWj66I+z67OgyIGRufqra8kSadXwBAqBi7y/Mh6jjs 90j2SGVbXYFnvHj3PZIZHx6AYRGfX11+lOPakGMzfTBJpggruWuLUeRQGE8zQUWwEZ kze+9Ar5CVyPA020jqeDr1unawXbAG33uyDZkt5DNUJXDv8/p7jJ/vwkX0399MZZh3 XVKqJAWXTq6EguODD1KtrBf/M4ws4PRRS0gBvBOIbDJpa2HDwEToz2lVdm0BWFcjQr P0RXT20T0R3Yg== From: SeongJae Park To: SeongJae Park Cc: Akinobu Mita , damon@lists.linux.dev Subject: Re: [RFC PATCH 0/4] mm/damon: introduce perf event based access check Date: Mon, 16 Feb 2026 16:13:23 -0800 Message-ID: <20260217001325.69633-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260128011225.71964-1-sj@kernel.org> References: Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On Tue, 27 Jan 2026 17:12:23 -0800 SeongJae Park wrote: > On Tue, 27 Jan 2026 21:56:43 +0900 Akinobu Mita wrote: > > > 2026年1月27日(火) 15:43 SeongJae Park : > > > Actually DAMON is internally setting such maximum region size based on the > > > min_nr_regions parameter, via damon_region_sz_limit(). Nonetheless, the limit > > > is applied only in regions merge time. That's why it requires the regions > > > split to happen sufficiently until the real fixed granularity monitoring is > > > started. > > > > > > And I think this behavior is just a bug, or suboptimum implementation at least. > > > That is, users set the minimum number of regions but it may not really be kept. > > > That's definitely confusing behavior. Actually there was a similar case that > > > number of regions can be larger than the max_nr_regions. We fixed it, with > > > commit 310d6c15e910 ("mm/damon/core: merge regions aggressively when > > > max_nr_regions is unmet"). I think we discussed about similar case for > > > min_nr_regions, but I cannot find the discussion for now. > > > > > > So, I think it is better to fix this rather than introducing a new parameter. > > > > I agree with that. > > > > > Maybe we can split regions based on the min_nr_regions based size limit, before > > > starting the main loop of kdamond_fn(). Similar to the max_nr_regions > > > violation, there could be yet another corner case on online parameters commit > > > situation, so it would better to check the case, too. You could implement such > > > fix on your own, or let me do that. In the latter case, if you don't mind, I > > > will add your Reported-by: tag to the fix. Please let me know your > > > preferrence. > > > > You'll be better able to fix it, so please fix it at your convenience. > > Adding Reported-by: tag is fine. > > Sounds good, I will do so! I just posted an RFC patch series [1] for this. I will drop RFC tag after the current merge window is finished. Please let me know if you find something wrong there! [1] https://lore.kernel.org/20260217000400.69056-1-sj@kernel.org Thanks, SJ [...]