From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lgeamrelo12.lge.com (lgeamrelo12.lge.com [156.147.23.52]) (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 179F9305047 for ; Mon, 13 Jul 2026 15:57:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=156.147.23.52 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783958260; cv=none; b=gw/8+AvMbbmWFHMkeGxjkeQPwL9ZMZ5hhaKhxl0UoMgZ8b3xFBVym7GpNPHLI7oD62qBLbxlUmMuzZ3mldi6ObBs9cwXHiMisZnhEOXyouQA3fHC33jNlrVVSptsK9ervCChuVO5Tx+5VzxJfyHRRnaRuul/idC6s/oPrOhAe7s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783958260; c=relaxed/simple; bh=PycK+6oCxCBM/cFgkMSak0eCHZUZ8ZvtRCwstKPB2ao=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=WCbSUrxshQHc7Cd387UzG9NTTLO/HNZEYPCGeqqcfaSKYe7GmvRNR6Nn5uKXMAos3CH0jRYHvX+FhVbBRGt9eD32abKvEZBj9XKLQvGgFqNttpOpIYiLFyx+T+aQwqK8pHbctkD4cqfS9wqxpCG326UDgz9Y26i0NThQRYdivGE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lge.com; spf=pass smtp.mailfrom=lge.com; arc=none smtp.client-ip=156.147.23.52 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lge.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=lge.com Received: from unknown (HELO lgeamrelo04.lge.com) (156.147.1.127) by 156.147.23.52 with ESMTP; 14 Jul 2026 00:57:36 +0900 X-Original-SENDERIP: 156.147.1.127 X-Original-MAILFROM: youngjun.park@lge.com Received: from unknown (HELO yjaykim-PowerEdge-T330) (10.177.112.156) by 156.147.1.127 with ESMTP; 14 Jul 2026 00:57:36 +0900 X-Original-SENDERIP: 10.177.112.156 X-Original-MAILFROM: youngjun.park@lge.com Date: Tue, 14 Jul 2026 00:57:36 +0900 From: Youngjun Park To: Yosry Ahmed Cc: akpm@linux-foundation.org, chrisl@kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kasong@tencent.com, hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, shikemeng@huaweicloud.com, baoquan.he@linux.dev, baohua@kernel.org, joshua.hahnjy@gmail.com, gunho.lee@lge.com, taejoon.song@lge.com, hyungjun.cho@lge.com, baver.bae@lge.com, her0gyugyu@gmail.com Subject: Re: [PATCH v10 0/6] mm/swap, memcg: Introduce swap tiers for cgroup based swap control Message-ID: References: <20260713025644.170839-1-youngjun.park@lge.com> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Mon, Jul 13, 2026 at 08:50:36AM -0700, Yosry Ahmed wrote: > On Sun, Jul 12, 2026 at 7:57 PM Youngjun Park wrote: > > > > This is the v10 series of the swap tier patchset. > > > > v10 folds in the Sashiko review fixes for the selftests added in v9 and > > rebases onto the current mm-new. There are no functional changes to the > > core swap or memcg code since v9; see the changelog for details. > > > > For context, the bulk of the series is unchanged since v8, with great thanks > > to Shakeel Butt and Yosry for the reviews and discussions [1] that shaped it. > > The main change in v8 was the interface change to use memory.swap.tiers.max > > with '0' (disable) and 'max' (enable) values. This mechanism was suggested > > by Shakeel and Yosry. > > > > This change allows for future extensions to control swap between tiers and > > aligns better with existing memcg interfaces. It is confined to patch #3's > > user-facing interface; internally, patch #3 still uses the existing mask > > processing method, which is implementation-efficient. > > > > We also discussed tier extensions. Thanks to Yosry, Nhat and Shakeel for their > > valuable feedback. > > > > Here is a brief summary of our tentative conclusions. Please correct me > > if anything is misrepresented (details in references): > > > > * Zswap tiering [2]: > > Zswap can itself be a tier (typically the fastest one). But, until vswap lands, > > zswap cannot be the only allowed tier, > > since it still needs a physical device for allocation; > > that restriction can be lifted once vswap is supported. > > Does this series support zswap being a tier? I cannot find any mention > of zswap in the patches. Hello Yosry! This series does not cover zswap as a tier yet. My plan is to land the swap tier infrastructure together with the first use case (cgroup-based swap control) first, and then follow up with zswap tier support in a subsequent series, continuing the discussions we've had above. (I mentioned on cover letter, right above the overview section) Does that approach sound reasonable to you?