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 9E023C77B7A for ; Wed, 7 Jun 2023 19:51:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232056AbjFGTvw (ORCPT ); Wed, 7 Jun 2023 15:51:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58384 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229980AbjFGTvt (ORCPT ); Wed, 7 Jun 2023 15:51:49 -0400 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B53871FFC for ; Wed, 7 Jun 2023 12:51:46 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-56536dd5f79so128010497b3.3 for ; Wed, 07 Jun 2023 12:51:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1686167506; x=1688759506; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=NDOi9DtrG3ImHyAY9qZt/+yVKhA3RZlvADlD5WArGHU=; b=1j0E5TB7ktv88hKTSJjc5mFVjUVL+4duocWh9tqI2JWOWupxXbkjIrlCv+0cHVwIIK H4nwE4R/ZdC9idZ46oaMCGJoMCi+6ILUzTNC+P7UMx1xRIxSvzJ7TmMvhjYjpN4eIbqN axzn6OzQ8nbwAO0OF/jCmu4Xrna7FB9NVCt97Fwg0pBXNfJXDspqzHe4Frhg8GCvzXhs /QVUduZQ3zptW3i11al2P0rOu1vrGgD8PhhyiJUWYIj2zYOdt2Td74Dw95n8AHEn1eY9 HjKMfbNRg7w26pGGDJN5/JOvRQOzS8pEM/qEW1tjPsPnIqmhwFlCeKwr/wKnevG1VQEh 8fPw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1686167506; x=1688759506; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=NDOi9DtrG3ImHyAY9qZt/+yVKhA3RZlvADlD5WArGHU=; b=AfykUzKICidy1tUITi/nLrcSQKaelOMOiyKMptYUzVNOaSrRqIdRes4enbf3UTH5ST 5NTTs/iIeapgwJpj/lG90pDy6rPONW/T2vTOnxzLJxWZ99KONIljhtb4//ebE98wVTqE uUSzHBc3isGjwaGlzIgDjf/AZeP/Z0aX+U5x0lBTV+oAB+b2JBbk4ffpGNZFVVDzCa4j xjH8ekOFP7bsnViDi7nN5ygOGIikNJYVyvUudXlq5wgpYV2KCYhGlb2PGsdStauu1JjB yG97YniiJ3O49J6EJphQE07aSF/mHFopn2GCN7rzI7IJPVAtlrAsm7Bk3A5UqU3yzjvW qeLQ== X-Gm-Message-State: AC+VfDw4iYjziNkph4q1P+hGfkFEGH9nW26yRBtJw4a7DFd+jSdC8cA2 +Ijx4oTDQhBsVLWxFsgn7fl/fpDeFZo5Hiij X-Google-Smtp-Source: ACHHUZ5Mkc+5WtR2XDfFpKKpGuzDmhAT6vsGdBhYndPwEaaJDfsBRWCIcgn73UeB7TSMMrzyW0RYHmyKl3E89BNw X-Received: from yosry.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:2327]) (user=yosryahmed job=sendgmr) by 2002:a05:690c:707:b0:565:a33a:a49f with SMTP id bs7-20020a05690c070700b00565a33aa49fmr3431292ywb.6.1686167505991; Wed, 07 Jun 2023 12:51:45 -0700 (PDT) Date: Wed, 7 Jun 2023 19:51:43 +0000 Mime-Version: 1.0 X-Mailer: git-send-email 2.41.0.162.gfafddb0af9-goog Message-ID: <20230607195143.1473802-1-yosryahmed@google.com> Subject: [PATCH v2 1/2] mm: zswap: support exclusive loads From: Yosry Ahmed To: Andrew Morton , Konrad Rzeszutek Wilk , Seth Jennings , Dan Streetman , Vitaly Wool Cc: Johannes Weiner , Nhat Pham , Domenico Cerasuolo , Yu Zhao , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Yosry Ahmed Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit 71024cb4a0bf ("frontswap: remove frontswap_tmem_exclusive_gets") removed support for exclusive loads from frontswap as it was not used. Bring back exclusive loads support to frontswap by adding an "exclusive" output parameter to frontswap_ops->load. On the zswap side, add a module parameter to enable/disable exclusive loads, and a config option to control the boot default value. Refactor zswap entry invalidation in zswap_frontswap_invalidate_page() into zswap_invalidate_entry() to reuse it in zswap_frontswap_load() if exclusive loads are enabled. With exclusive loads, we avoid having two copies of the same page in memory (compressed & uncompressed) after faulting it in from zswap. On the other hand, if the page is to be reclaimed again without being dirtied, it will be re-compressed. Compression is not usually slow, and a page that was just faulted in is less likely to be reclaimed again soon. Suggested-by: Yu Zhao Signed-off-by: Yosry Ahmed --- v1 -> v2: - Add a module parameter to control whether exclusive loads are enabled or not, the config option now controls the default boot value instead. Replaced frontswap_ops->exclusive_loads by an output parameter to frontswap_ops->load() (Johannes Weiner). --- include/linux/frontswap.h | 2 +- mm/Kconfig | 16 ++++++++++++++++ mm/frontswap.c | 10 ++++++++-- mm/zswap.c | 28 ++++++++++++++++++++-------- 4 files changed, 45 insertions(+), 11 deletions(-) diff --git a/include/linux/frontswap.h b/include/linux/frontswap.h index a631bac12220..eaa0ac5f9003 100644 --- a/include/linux/frontswap.h +++ b/include/linux/frontswap.h @@ -10,7 +10,7 @@ struct frontswap_ops { void (*init)(unsigned); /* this swap type was just swapon'ed */ int (*store)(unsigned, pgoff_t, struct page *); /* store a page */ - int (*load)(unsigned, pgoff_t, struct page *); /* load a page */ + int (*load)(unsigned, pgoff_t, struct page *, bool *); /* load a page */ void (*invalidate_page)(unsigned, pgoff_t); /* page no longer needed */ void (*invalidate_area)(unsigned); /* swap type just swapoff'ed */ }; diff --git a/mm/Kconfig b/mm/Kconfig index 7672a22647b4..12f32f8d26bf 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -46,6 +46,22 @@ config ZSWAP_DEFAULT_ON The selection made here can be overridden by using the kernel command line 'zswap.enabled=' option. +config ZSWAP_EXCLUSIVE_LOADS_DEFAULT_ON + bool "Invalidate zswap entries when pages are loaded" + depends on ZSWAP + help + If selected, exclusive loads for zswap will be enabled at boot, + otherwise it will be disabled. + + If exclusive loads are enabled, when a page is loaded from zswap, + the zswap entry is invalidated at once, as opposed to leaving it + in zswap until the swap entry is freed. + + This avoids having two copies of the same page in memory + (compressed and uncompressed) after faulting in a page from zswap. + The cost is that if the page was never dirtied and needs to be + swapped out again, it will be re-compressed. + choice prompt "Default compressor" depends on ZSWAP diff --git a/mm/frontswap.c b/mm/frontswap.c index 279e55b4ed87..2fb5df3384b8 100644 --- a/mm/frontswap.c +++ b/mm/frontswap.c @@ -206,6 +206,7 @@ int __frontswap_load(struct page *page) int type = swp_type(entry); struct swap_info_struct *sis = swap_info[type]; pgoff_t offset = swp_offset(entry); + bool exclusive = false; VM_BUG_ON(!frontswap_ops); VM_BUG_ON(!PageLocked(page)); @@ -215,9 +216,14 @@ int __frontswap_load(struct page *page) return -1; /* Try loading from each implementation, until one succeeds. */ - ret = frontswap_ops->load(type, offset, page); - if (ret == 0) + ret = frontswap_ops->load(type, offset, page, &exclusive); + if (ret == 0) { inc_frontswap_loads(); + if (exclusive) { + SetPageDirty(page); + __frontswap_clear(sis, offset); + } + } return ret; } diff --git a/mm/zswap.c b/mm/zswap.c index 59da2a415fbb..bfbcedce9c89 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -137,6 +137,10 @@ static bool zswap_non_same_filled_pages_enabled = true; module_param_named(non_same_filled_pages_enabled, zswap_non_same_filled_pages_enabled, bool, 0644); +static bool zswap_exclusive_loads_enabled = IS_ENABLED( + CONFIG_ZSWAP_EXCLUSIVE_LOADS_DEFAULT_ON); +module_param_named(exclusive_loads, zswap_exclusive_loads_enabled, bool, 0644); + /********************************* * data structures **********************************/ @@ -1329,12 +1333,22 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset, goto reject; } +static void zswap_invalidate_entry(struct zswap_tree *tree, + struct zswap_entry *entry) +{ + /* remove from rbtree */ + zswap_rb_erase(&tree->rbroot, entry); + + /* drop the initial reference from entry creation */ + zswap_entry_put(tree, entry); +} + /* * returns 0 if the page was successfully decompressed * return -1 on entry not found or error */ static int zswap_frontswap_load(unsigned type, pgoff_t offset, - struct page *page) + struct page *page, bool *exclusive) { struct zswap_tree *tree = zswap_trees[type]; struct zswap_entry *entry; @@ -1404,6 +1418,10 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset, freeentry: spin_lock(&tree->lock); zswap_entry_put(tree, entry); + if (!ret && zswap_exclusive_loads_enabled) { + zswap_invalidate_entry(tree, entry); + *exclusive = true; + } spin_unlock(&tree->lock); return ret; @@ -1423,13 +1441,7 @@ static void zswap_frontswap_invalidate_page(unsigned type, pgoff_t offset) spin_unlock(&tree->lock); return; } - - /* remove from rbtree */ - zswap_rb_erase(&tree->rbroot, entry); - - /* drop the initial reference from entry creation */ - zswap_entry_put(tree, entry); - + zswap_invalidate_entry(tree, entry); spin_unlock(&tree->lock); } -- 2.41.0.162.gfafddb0af9-goog