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 3695BC4332F for ; Tue, 7 Nov 2023 18:33:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343738AbjKGSd6 (ORCPT ); Tue, 7 Nov 2023 13:33:58 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38448 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232861AbjKGSdv (ORCPT ); Tue, 7 Nov 2023 13:33:51 -0500 Received: from mail-qk1-x72b.google.com (mail-qk1-x72b.google.com [IPv6:2607:f8b0:4864:20::72b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1C2CD13A for ; Tue, 7 Nov 2023 10:33:49 -0800 (PST) Received: by mail-qk1-x72b.google.com with SMTP id af79cd13be357-777719639adso386214485a.3 for ; Tue, 07 Nov 2023 10:33:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20230601.gappssmtp.com; s=20230601; t=1699382028; x=1699986828; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=8avTRAw+qJM+8GGepFLeKQe8V+ZhPn3lvGUNQHQn6cU=; b=yIUeXeYCR8+IvzqbBHzgNiZxjiwRGDDP+qr3mSKG6xMPnrqk9cN9BeOSHjCI03BFUq v572k2Nwks11alnC9xIWvOTeHqvH4VHiJ22Ysny8mDZP832kbE5COa6YX1r9D7tl13fl jp8QAHnhswRo8ofdCVwDHnfKaW0ETmbRQnaH3PjzA+Sek1cATn5gLgKwg6g4l0aIqiu+ 42IAd/Ld+bzj2it0TS/lUTtyhWEy1ofuUhpCWKezOD0YJhQ6dYhOqWHzgypgGV3imnG8 6ktUJCrgZrWeqYmpBJbep3jaf85gq26FfEM0CiJ8V8cmgNK4Jm8A5z+R+U7uEe0/3eJ7 LdRg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1699382028; x=1699986828; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=8avTRAw+qJM+8GGepFLeKQe8V+ZhPn3lvGUNQHQn6cU=; b=BbksefGdhePX3XQcwwp8mMfng8g25u+4ema4eJea5Ftgz6DUK5MLqtP1kzRZM0cLY6 Em0mQOq5SLTRbmNXXoH0XF7QP+hvh6vWX/fGFJf9ameWSnZOnd7+eY+h+y4xP/LHSM6u bbL0fKzgWsxOJoUE2pn8aEtrvWNfbWQsf7bNWsUp//gTjTHLSo4STgrp83BgLVz8iBCx H4ojkOeyak3gJkdyTJNI8sAzjxo2o36QG7PoW5Pybm/KY/smmEdYC+nOxP7SA+owMUCm qf7jmD8HIriWoMyB5faqO/gWL4rWQA2i+ep0Am2wVynBvSiyGgmCINra1y3kobhILlCI Qpag== X-Gm-Message-State: AOJu0YyThI/zvyL2gNjwg1fyuNz2c44rDK6/Gbe2Hb39ptW6oWYFmekN /kjq5sg5bEMAEavKlA2hfcGwGQ== X-Google-Smtp-Source: AGHT+IH01xrkUfmAz5hEXZhH23UNWoyA7VRhKDTDM4x2eoKe8MdyAO1UMYAPhWv6pWRLzrBzISOJbQ== X-Received: by 2002:a05:6214:f04:b0:66d:9d28:3686 with SMTP id gw4-20020a0562140f0400b0066d9d283686mr41129341qvb.53.1699382028083; Tue, 07 Nov 2023 10:33:48 -0800 (PST) Received: from localhost ([2620:10d:c091:400::5:86b7]) by smtp.gmail.com with ESMTPSA id j2-20020a056214022200b00670f8570a24sm157124qvt.23.2023.11.07.10.33.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 Nov 2023 10:33:47 -0800 (PST) Date: Tue, 7 Nov 2023 13:33:46 -0500 From: Johannes Weiner To: Hyeongtak Ji Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hyeongtak Ji Subject: Re: [PATCH] mm/vmscan: consider previously reclaimed pages in shrink_lruvec() Message-ID: <20231107183346.GA3789583@cmpxchg.org> References: <1691402476-4838-1-git-send-email-hyeongtak.ji@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1691402476-4838-1-git-send-email-hyeongtak.ji@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 07, 2023 at 07:01:16PM +0900, Hyeongtak Ji wrote: > shrink_lruvec() currently ignores previously reclaimed pages in > scan_control->nr_reclaimed. This can lead shrink_lruvec() to reclaiming > more pages than expected. > > This patch fixes shrink_lruvec() to take into account the previously > reclaimed pages. Do you run into real world issues from this? The code has been like this for at least a decade. It's an intentional choice to ensure fairness across all visited cgroups. sc->nr_to_reclaim is 32 pages or less - it's only to guard against extreme overreclaim. But we want to make sure we reclaim a bit from all cgroups, rather than always hit the first one and then bail.