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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9CF78C54798 for ; Fri, 8 Mar 2024 00:15:06 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DA15E6B02E1; Thu, 7 Mar 2024 19:15:05 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id D518E6B02E2; Thu, 7 Mar 2024 19:15:05 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C40A46B02E3; Thu, 7 Mar 2024 19:15:05 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id B3CD76B02E1 for ; Thu, 7 Mar 2024 19:15:05 -0500 (EST) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 91BDA1211DC for ; Fri, 8 Mar 2024 00:15:05 +0000 (UTC) X-FDA: 81871951770.24.2126675 Received: from mail-oa1-f49.google.com (mail-oa1-f49.google.com [209.85.160.49]) by imf18.hostedemail.com (Postfix) with ESMTP id 751591C0018 for ; Fri, 8 Mar 2024 00:15:03 +0000 (UTC) Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=JRSo6jlk; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf18.hostedemail.com: domain of jaredeh@gmail.com designates 209.85.160.49 as permitted sender) smtp.mailfrom=jaredeh@gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1709856903; a=rsa-sha256; cv=none; b=oapkS5zPIc9GXS3rRjusz+owWSsxa2jN58RTUbhF232iNFpUrk92RnnYmIxBs2cOz0bd2H 36Ed84uMku0jqIGWE06rjd5wkjI1zf3oEWChykDhVBO7GstUi4dgX0zDgOhWe+VHy5adjk 7Fp1OhuVRMYEUhVWAIUedrn3maANNkI= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=JRSo6jlk; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf18.hostedemail.com: domain of jaredeh@gmail.com designates 209.85.160.49 as permitted sender) smtp.mailfrom=jaredeh@gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1709856903; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=kXQkz2DsNjSMYSB7S6M6mJFSpwaBKfl8vvxQFZH9Hps=; b=E6Tm52Y4HiH829W9obg6FqLk5QDpYHk4K9IY2O5f0Y6yCG5Xjv3GC5xgds4eu3PVJosjp5 pgEZCGeORWShcSmXskrRg1EsnusyyQmyeTXzei8FiSrLMEl4yzImeRB8MtzbCQchvzh0xI MS3v9U7L68CGv8etp1Zv7ioDK72ChIo= Received: by mail-oa1-f49.google.com with SMTP id 586e51a60fabf-2210865d962so182888fac.3 for ; Thu, 07 Mar 2024 16:15:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1709856902; x=1710461702; darn=kvack.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=kXQkz2DsNjSMYSB7S6M6mJFSpwaBKfl8vvxQFZH9Hps=; b=JRSo6jlk6Si2X8pPIwKTonfYT7TNxgGHudu7QdSWttXj7MKE8Ry00rfG2Pnc2HbYcf pmdzQodso/OwUouZJAoA3Wd4mOJwXyqVO3G8Ez5UiAabpS+CsPuZ2eVYiIYLqCPCSqCJ /1+VBGu2cWTYatbSOCoAYQcnIO9GJt3uvRMeLd+B9k8bil6RWoLv5m2TyJSpa7jgQVzg Ls3Tns1w2l+UdIdBMCPH0On2tx5Xn7a3Z/D/qk9e4aQuTkF0d4l5qKmr1l+GsmwuHm48 Xe5R1v1vsTUgh6Xbvd/BvX/AlYNFfK51qJhIIHRD9rOWmjNGDukWmz7eGXznhR4k5ZUy Pz7Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1709856902; x=1710461702; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=kXQkz2DsNjSMYSB7S6M6mJFSpwaBKfl8vvxQFZH9Hps=; b=PPag5XTeUAfZbeDBo9ibszU0SFcVpMbgICW+k09x3uXy+a1KHdy/T0v74+VdVM9KFH z+HqVAGQNdvcuX/F2Pvp59rw7mMWSk1GlqT8obHCvjk1bQ8EvDR2VJguF2VzyDYbsUT+ /wnxa+ZPUMV3nfNJ/hA+YPFhTBNzkri3CX1uWsi9/RtbUZ593WwmR6deqwlrdL2g3Wk5 4oEDavQ6uykpWuURUgn198DWBSc0orsimIkM3IWbqKFGbgX3MWqFmsSwXiLwowjCPI0P oyED77B0c2lKXQNaWOsSSoGZ4loCEPOwNWfEH8rn8q9rq3PPIcBje1gFfFLOdKqaZ7sQ VGfQ== X-Forwarded-Encrypted: i=1; AJvYcCXBueQoBsAVzttcbKlLmzd68vEyNDIkld7U6jo6k9Z4K0hOwpOsEvMd1HPy+mNq4b9RmF2UOutXI9MfnG7SyoHobwo= X-Gm-Message-State: AOJu0YzgLTEvfoSkz6LNp5EZIycvacNbA3YMNYVL6B2PpN6hI+gkIKd2 WQ0sDAkDhVuadcWNIUrthmg3hRzoYB1vhbVA2/PVg2gcSWuE9oNnyYn8Xax4FxaFXW47GP5fwJs MXez+tsTiY8Oa6T1WoIoWZFvM9pU= X-Google-Smtp-Source: AGHT+IGf/bnit7c+e0T5Ul0NuWnoccTBLMk2NJ71uJDPqKmRujfXK7O6xVNyCI/UpaxNuwEmSIAh6TDMV/acFYtK458= X-Received: by 2002:a05:6870:4708:b0:221:3bb8:3e26 with SMTP id b8-20020a056870470800b002213bb83e26mr1490518oaq.15.1709856901615; Thu, 07 Mar 2024 16:15:01 -0800 (PST) MIME-Version: 1.0 References: <039190fb-81da-c9b3-3f33-70069cdb27b0@oppo.com> <20240307140344.4wlumk6zxustylh6@quack3> In-Reply-To: From: Jared Hulbert Date: Thu, 7 Mar 2024 16:14:50 -0800 Message-ID: Subject: Re: [Lsf-pc] [LSF/MM/BPF TOPIC] Swap Abstraction "the pony" To: Barry Song <21cnbao@gmail.com> Cc: Jan Kara , Chuanhua Han , Chris Li , linux-mm , lsf-pc@lists.linux-foundation.org, ryan.roberts@arm.com, david@redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 751591C0018 X-Stat-Signature: 1ufqdpj1sw8sry6afpzthw4gogy1gjdr X-HE-Tag: 1709856903-856636 X-HE-Meta: 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.002562, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Mar 7, 2024 at 1:17=E2=80=AFPM Barry Song <21cnbao@gmail.com> wrote= : > > I don't understand why we need this level of complexity. All we need to k= now > are the offsets during pageout. After that, the large folio is > destroyed, and all > offsets are stored in page table entries (PTEs) or xa. Swap-in doesn't de= pend > on a complex file system; it can make its own decision on how to swap-in > based on the values it reads from PTEs. > > Swap-in doesn't need to know whether the swapped-out folio was large or n= ot. Right if the folio was broken down to individual pages on swap out then individual pages PTEs know where the data is. So I agree it's not necessary. But the folio was destroyed. We want to recreate the folio on swap in? IDK \What if you flip the argument? The complexity of the file path exists already... If swap didn't exist could we justify adding the duplicated (albeit simpler) functionality of swap?