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 C283A227EB9; Wed, 4 Feb 2026 07:17:14 +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=1770189434; cv=none; b=mQVLt4nnzeywR8GuWuYvhHZsvPNeNtxNs0xxja0PRQ2uqRH49etUBMG4dDz7eJbsLUAs4dAa1xa9kjDF9Tz1Q2X/qh8n9uqWGDpfuFLDNqVQl7Fhu3MMbeLk0TsD/hglQdYpFu0p6dV0OPqvd91K2V+Q1ZWM8KrqOpU6hNgwTwo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770189434; c=relaxed/simple; bh=PbpHINPIxKlo9HPoQQXP6SMwz/+sggXsDbHwfHXEEkM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ZiDnwuIKzXI4guxC2Qd1oSAO99YlpeOB3CgQiI59OiR7uNUQwOURoAWrsYU1ZLrMMBxZJcXhmEuV5gtNTN8EYhqz0SgVKAfUUA56SOeWnsssUVozmREB+ZqC1pA2Yljd8TEhhA+z6XQa4N7Ft9JMkLEm+rrB9i8Kw+7STrqz3BQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=alX5ja/r; 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="alX5ja/r" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4028CC4CEF7; Wed, 4 Feb 2026 07:17:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770189434; bh=PbpHINPIxKlo9HPoQQXP6SMwz/+sggXsDbHwfHXEEkM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=alX5ja/rxhvf5yBZcCNXHG6rAaG5VEkuC40wnmWvqMN6tM20LdqGLTogEH39uhSgK H/Q9S7C8aF1gsQKYdz1rjlPs0uHp8T5ZY1vGAiHOEhZtXr3O3jM9ytNzuozft2XdPj CFnhrg65NijjL3rspj1ZmBNWZzWV2ACtewNPl+b0+SXsRupHsfoLW1jd/c/dm9vmX7 Z96d40SD/Ob8bq89SOm6B2UEOncXijT9pARMFVg6wnaOLyw4sqAnFwSxtCEyuk5+vV LpKs3AxRrLThnBl1CCr6m7V7lSwiF3Bc2jZXElLj9ZO6REzoVMBVZM03dkLzYR5dke VQphjGTIq7o7Q== From: SeongJae Park To: Gutierrez Asier Cc: SeongJae Park , artem.kuzin@huawei.com, stepanov.anatoly@huawei.com, wangkefeng.wang@huawei.com, yanquanmin1@huawei.com, zuoze1@huawei.com, damon@lists.linux.dev, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v1 0/4] mm/damon: Support hot application detections Date: Tue, 3 Feb 2026 23:17:11 -0800 Message-ID: <20260204071712.16325-1-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 Tue, 3 Feb 2026 17:25:11 +0300 Gutierrez Asier wrote: > SeongJae, > > Thanks a lot for all the useful feedback. The pleasure is mine! :) > > One thing that I was not sure about while working on this patch set > is whether to have an external new module or adding the logic to > damon core. I mean, the hot application detecting can be useful for > all other modules and can improve DAMON performance. All exising non-sample DAMON modules are working for the physical address space. I hence finding no many opportunities to bring benefits of hot application detection to those. I agree the hot applications detection could be useful in general and creative DAMON use cases for virtual address spaces. Implementing the feature in DAMON core layer and exposing it via DAMON sysfs interface will help such use cases. But it seems not straightforward to imagine how the sysfs interface can be extended for the feature. So, I think it would better to be implemented inside the new module at the moment. Later, if we end up having more modules that use the feature, we could move it to the modules-common or the core. If we further find a good way to integrate that with sysfs interface, definitely it could go to core. >From this point, however, I realize the feature can also be implemented in the user sapce in a pretty straightforward way. Have you considered that? > What do you think? > My implementation was module based because I tried to avoid changes > to DAMON core for the RFC. If there is a good reason to implement that not in the user space but the kernel space, as I mentioned above, it seems the module is the right place to me. Thanks, SJ [...]