From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A0C9DC433FE for ; Sun, 3 Apr 2022 06:46:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353747AbiDCGsg (ORCPT ); Sun, 3 Apr 2022 02:48:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34984 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237957AbiDCGse (ORCPT ); Sun, 3 Apr 2022 02:48:34 -0400 Received: from mail-il1-x12d.google.com (mail-il1-x12d.google.com [IPv6:2607:f8b0:4864:20::12d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3AFB237BC2 for ; Sat, 2 Apr 2022 23:46:41 -0700 (PDT) Received: by mail-il1-x12d.google.com with SMTP id e13so978613ils.8 for ; Sat, 02 Apr 2022 23:46:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=t6+k/4Om7VsqLidja8hb8+QMIWaL5Tmj1wC2cL00ays=; b=nOlAijP5ZZ9vsdwJxJUZqAvchhR2fSeQGoSus10DZCtVRxLYXfh3CaMWft73tMME1m t8EEPpLhVAmbmIitm4y9QYf8gD29WnqYP9IPk0DbsJRQ306l1QfJlfZBvwV0n6/apy1q kE/dBq22AAuWR+VBcGZKlXr/FEVoU2mgB22M1LxnKoR+KLx+gi822+ieZ9bQV5DPkPDX rv0cbX0UhZ/st6FHWyCx4nSEY24sHkWVOJgCK96qcxkxAp+J+AvawMuPwG3FbWM+qvsh z1YzQW9HvQJnNjv85bt720LiaBD3IDsndMwp3VULMTwSwWfSyKEqFX+sUpd6E8sAOFuU nD8g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=t6+k/4Om7VsqLidja8hb8+QMIWaL5Tmj1wC2cL00ays=; b=kBGWs3PTXok2hx0G01TUJ9q9yvkRJvf2dJB/akPeLMK+asohtkI76ktWo1l5r017IY ylkV5svoK8lVO3JMyNOtGxHtl4NyL4limJTimVOKqlLgRvm1xW1CsOKNXxYJCypwuBP9 jjaUVbjIbWpuh45sJx/MjD7EtRhtuIGGzUCgUjnxTyKE86upq+Z2I5nrzVW74OWEaJxi I0G+4Pflz6QRGpHRGg/whBGlxux9B+iQhd/IQqBACWG0d6z4Vx6QXsfqC9FV1BkeN8w2 Sa5ur61XbfL4NyzcHZVk7kDAdhPqjLb1HYGv7/9uOz0HTo/vn+etkUWySZL/BD0RlfSN JnMA== X-Gm-Message-State: AOAM533QJLyuCy81klYMtxh74D7msme9eF/YvyTZ6RtI6aPnjVad0RZp 7XoBSq7sLP9GJ8xPmFEtrXbzyCWBQQP06QQphEsqlX/SbkQ= X-Google-Smtp-Source: ABdhPJzFIevVMEisQ9Pwvrh3Lhxnl9EwRG1TSPfzOF/+7Ua2Imr8RieK1XhYkaSWk0BECbaP9FsQ3vwbj4/V5Fwy9OA= X-Received: by 2002:a92:d94d:0:b0:2c8:45a5:926b with SMTP id l13-20020a92d94d000000b002c845a5926bmr3208155ilq.310.1648968400437; Sat, 02 Apr 2022 23:46:40 -0700 (PDT) MIME-Version: 1.0 References: <20220331084151.2600229-1-yosryahmed@google.com> <87y20nzyw4.fsf@yhuang6-desk2.ccr.corp.intel.com> In-Reply-To: <87y20nzyw4.fsf@yhuang6-desk2.ccr.corp.intel.com> From: Wei Xu Date: Sat, 2 Apr 2022 23:46:29 -0700 Message-ID: Subject: Re: [PATCH resend] memcg: introduce per-memcg reclaim interface To: "Huang, Ying" Cc: Michal Hocko , Yosry Ahmed , Johannes Weiner , Shakeel Butt , Andrew Morton , David Rientjes , Tejun Heo , Zefan Li , Roman Gushchin , cgroups@vger.kernel.org, linux-doc@vger.kernel.org, Linux Kernel Mailing List , Linux MM , Jonathan Corbet , Yu Zhao , Dave Hansen , Greg Thelen Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Apr 2, 2022 at 1:13 AM Huang, Ying wrote: > > Wei Xu writes: > > > On Fri, Apr 1, 2022 at 6:54 AM Michal Hocko wrote: > >> > >> On Thu 31-03-22 08:41:51, Yosry Ahmed wrote: > >> > From: Shakeel Butt > >> > > > [snip] > > >> > Possible Extensions: > >> > -------------------- > >> > > >> > - This interface can be extended with an additional parameter or flags > >> > to allow specifying one or more types of memory to reclaim from (e.g. > >> > file, anon, ..). > >> > > >> > - The interface can also be extended with a node mask to reclaim from > >> > specific nodes. This has use cases for reclaim-based demotion in memory > >> > tiering systens. > >> > > >> > - A similar per-node interface can also be added to support proactive > >> > reclaim and reclaim-based demotion in systems without memcg. > >> > > >> > For now, let's keep things simple by adding the basic functionality. > >> > >> Yes, I am for the simplicity and this really looks like a bare minumum > >> interface. But it is not really clear who do you want to add flags on > >> top of it? > >> > >> I am not really sure we really need a node aware interface for memcg. > >> The global reclaim interface will likely need a different node because > >> we do not want to make this CONFIG_MEMCG constrained. > > > > A nodemask argument for memory.reclaim can be useful for memory > > tiering between NUMA nodes with different performance. Similar to > > proactive reclaim, it can allow a userspace daemon to drive > > memcg-based proactive demotion via the reclaim-based demotion > > mechanism in the kernel. > > I am not sure whether nodemask is a good way for demoting pages between > different types of memory. For example, for a system with DRAM and > PMEM, if specifying DRAM node in nodemask means demoting to PMEM, what > is the meaning of specifying PMEM node? reclaiming to disk? > > In general, I have no objection to the idea in general. But we should > have a clear and consistent interface. Per my understanding the default > memcg interface is for memory, regardless of memory types. The memory > reclaiming means reduce the memory usage, regardless of memory types. > We need to either extending the semantics of memory reclaiming (to > include memory demoting too), or add another interface for memory > demoting.