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 X-Spam-Level: X-Spam-Status: No, score=-20.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 55FB6C4338F for ; Thu, 22 Jul 2021 21:21:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 315D760EB5 for ; Thu, 22 Jul 2021 21:21:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231462AbhGVUk7 (ORCPT ); Thu, 22 Jul 2021 16:40:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56798 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231260AbhGVUky (ORCPT ); Thu, 22 Jul 2021 16:40:54 -0400 Received: from mail-pj1-x1036.google.com (mail-pj1-x1036.google.com [IPv6:2607:f8b0:4864:20::1036]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 74B8CC061575 for ; Thu, 22 Jul 2021 14:21:29 -0700 (PDT) Received: by mail-pj1-x1036.google.com with SMTP id gv20-20020a17090b11d4b0290173b9578f1cso4550352pjb.0 for ; Thu, 22 Jul 2021 14:21:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=xPGY9e0OQBf+7CM81A58drfZzUib4cbQB7IlfwfQYK4=; b=a5KVrzocDZ0oWxT2cMqSHag9+OsgsPRJJk0CuDZ7cArI6yiIK/nMcUu8Lf22ZcVZ1u xVyQJ4+Lm4opIjOpSJ8sGwjnegzyWpZ+0IOrUzAkvT4JqZLT2DTOoOSYijXiu9mrdh6Z xrqi4Dv6D7kuanBnaQs3Xuazl4drRGcGS1JJo= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=xPGY9e0OQBf+7CM81A58drfZzUib4cbQB7IlfwfQYK4=; b=lsL1dFm46WesG3T95NJYeAMc304uynpqpvZozfHznnAhC+WTavSVF2Ys/8l97gqFrH FgiuaG5F8mRfk5fGYRZUC1HQMPntTK0ZO8Ze6Fe6PoVfscf7Bjd9jj2DciQBv/aH8Bo3 RBhsnG4UGpAQrS9LxxH7PnTKLCJSOI4t3LtheU0/GNUQ1VtzmNbkkOJTtQ9nX8g6ZLfF Sflt/7ZOv/kcDGrTlKn5kloRZUIyCLzJPkpggpHbeIXKW+mdBueJeOsG9t12jSKOFXYv lRDbDUYahMDr17eRsaiTx19bfKeegbBzDCTEfAMYgW2BYmNKfgN1VComwF/YswxafK9d 5IOw== X-Gm-Message-State: AOAM5317E5PP4lJo8PwtcRrC+EUD9kMMQ8QCKyCPrpFafNorH1aeSUC9 Mst7dI34EXH1tLl9gQo3d+Tvcz5toamC5A== X-Google-Smtp-Source: ABdhPJwwJe1I8pqQz7Xl58xlzbzVSks0vM8Tc9Q/BAUpyYmojmilX8DEU6noswrtvqUrtzSR4lri1Q== X-Received: by 2002:a17:90a:3e81:: with SMTP id k1mr2991384pjc.177.1626988888781; Thu, 22 Jul 2021 14:21:28 -0700 (PDT) Received: from evgreen-glaptop.lan ([2601:646:c780:5ba8:87e4:35cd:ee1f:5965]) by smtp.gmail.com with ESMTPSA id kz18sm26566365pjb.49.2021.07.22.14.21.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Jul 2021 14:21:28 -0700 (PDT) From: Evan Green To: linux-man@vger.kernel.org Cc: Andrew Morton , Evan Green Subject: [PATCH] swapon.2: Document NOSWAP and additional DISCARD flags Date: Thu, 22 Jul 2021 14:21:20 -0700 Message-Id: <20210722212120.3060163-1-evgreen@chromium.org> X-Mailer: git-send-email 2.31.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-man@vger.kernel.org Fix the FIXME and finally document SWAP_FLAG_DISCARD_ONCE and SWAP_FLAG_DISCARD_PAGES from Linux 3.11. Additionally, document SWAP_FLAG_NOSWAP, a shiny new flag being introduced in Linux 5.14. See the following link: https://lore.kernel.org/lkml/20210721143946.v3.1.I09866d90c6de14f21223a03e9e6a31f8a02ecbaf@changeid/ Signed-off-by: Evan Green --- man2/swapon.2 | 33 ++++++++++++++++++++++++++------- 1 file changed, 26 insertions(+), 7 deletions(-) diff --git a/man2/swapon.2 b/man2/swapon.2 index 07d5fe86c..d568da993 100644 --- a/man2/swapon.2 +++ b/man2/swapon.2 @@ -33,13 +33,10 @@ .\" 2004-12-14 mtk, Anand Kumria: added new errors .\" 2007-06-22 Ivana Varekova , mtk .\" Update text describing limit on number of swap files. +.\" 2021-07-22 Evan Green +.\" Document _DISCARD_ONCE, _DISCARD_PAGES, and _NOSWAP flags. .\" -.\" FIXME Linux 3.11 added SWAP_FLAG_DISCARD_ONCE and SWAP_FLAG_DISCARD_PAGES -.\" commit dcf6b7ddd7df8965727746f89c59229b23180e5a -.\" Author: Rafael Aquini -.\" Date: Wed Jul 3 15:02:46 2013 -0700 -.\" -.TH SWAPON 2 2021-03-22 "Linux" "Linux Programmer's Manual" +.TH SWAPON 2 2021-07-22 "Linux" "Linux Programmer's Manual" .SH NAME swapon, swapoff \- start/stop swapping to file/device .SH SYNOPSIS @@ -81,9 +78,23 @@ flag is specified in the argument, freed swap pages will be discarded before they are reused, if the swap device supports the discard or trim operation. (This may improve performance on some Solid State Devices, -but often it does not.) +but often it does not.) In conjunction with this flag, callers may add +.B SWAP_FLAG_DISCARD_ONCE +to perform a single discard over the entire region at swapon time, and/or +.B SWAP_FLAG_DISCARD_PAGES +to perform discards as swap pages are freed. If neither is specified, +both are assumed. See also NOTES. .PP +If the +.B SWAP_FLAG_NOSWAP +flag is specified in the +.BR swapon () +.I swapflags +argument, then the added swap region will not be eligible for regular +swap activities. It can still be used for hibernate, enabling callers +to steer the swap and hibernate regions independently. +.PP These functions may be used only by a privileged process (one having the .B CAP_SYS_ADMIN capability). @@ -201,6 +212,14 @@ which still discards the entire swap area when .BR swapon () is called, even if that flag bit is not set. +.PP +.B SWAP_FLAG_DISCARD_ONCE +and +.B SWAP_FLAG_DISCARD_PAGES +were introduced in Linux 3.11. +.PP +.B SWAP_FLAG_NOSWAP +was introduced in Linux 5.14. .SH SEE ALSO .BR mkswap (8), .BR swapoff (8), -- 2.31.0