From patchwork Mon Apr 3 20:18:38 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zi Yan X-Patchwork-Id: 13198704 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 56310C76188 for ; Mon, 3 Apr 2023 20:19:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233106AbjDCUTN (ORCPT ); Mon, 3 Apr 2023 16:19:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54972 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232943AbjDCUTJ (ORCPT ); Mon, 3 Apr 2023 16:19:09 -0400 Received: from out3-smtp.messagingengine.com (out3-smtp.messagingengine.com [66.111.4.27]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 93EDD30F2; Mon, 3 Apr 2023 13:19:08 -0700 (PDT) Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by mailout.nyi.internal (Postfix) with ESMTP id F34585C012D; Mon, 3 Apr 2023 16:19:07 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute3.internal (MEProxy); Mon, 03 Apr 2023 16:19:07 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sent.com; h=cc :cc:content-transfer-encoding:content-type:date:date:from:from :in-reply-to:in-reply-to:message-id:mime-version:references :reply-to:reply-to:sender:subject:subject:to:to; s=fm2; t= 1680553147; x=1680639547; bh=n0I3rKbVmW11Ko5MdyrWnLEXy5CTcBBnWUT tQZPt4TU=; b=CknXjAfEg+BlpRI36eBMzyBQgGufPONGhPvWy7s+gy/bhNUeDoy XrZZS36kGlcl7YvPRJZxh2QYUhLMrXCglMzsbdi6caUVkB32GPU136oGWOw9D7FN a8wMhxHbFNmlt1qrJ4P/OxqrHkHDhHurwSRTuukUPsm7F/OfAzu7PwJdwNe7hY1d dOGCKNRadN2+ZLi0jXCvtfukxAs0chGy99+JG1ewv3jNM2OLkjwCNlw0I19tiNiQ FnGOZayjMtLBHucHfEbFGOi/9g1Wg+PAq0cU0Ne/rfk5Pt2zZn8rEnuff6x7Lwtq wL12JuQLFZHNFUdi0ohPgNaCwuQhZRPtcow== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-transfer-encoding :content-type:date:date:feedback-id:feedback-id:from:from :in-reply-to:in-reply-to:message-id:mime-version:references :reply-to:reply-to:sender:subject:subject:to:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; t= 1680553147; x=1680639547; bh=n0I3rKbVmW11Ko5MdyrWnLEXy5CTcBBnWUT tQZPt4TU=; b=hNICcSGN1EXXDV3uYu5QpP5/qwn5lAAgv19FTzFTRbX5N0FlNAD +5Ly6h8+eRZyyrSEBPSN01hlDZia4jeE8G0YMvkRUcpZK9YRyKP43ep+HjxUeE20 azKRsRgrYvZ0GHFOvtBFsAnC1eAK617AZaxsoAL4N0/2EGRvbUPQr0Hgug9brVGx wq1vCYXFWpRBjdnVF9SmQ0OIxtvSSxi76UNt/wFGEF57YmmJAUg0kBVUaVJRBARw Peey3G6reNzAV18EFN4QhsoRg4Ow1+bNDTN5r17diEi2jc8HfCGGMbSUEL0f0Ikv GUwL+HnFRkobihhK9fbtiKJ902159F8YvgA== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvhedrvdeijedgudegkecutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfgh necuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd enucfjughrpefhvfevufffkffojghfrhgggfestdhqredtredttdenucfhrhhomhepkghi ucgjrghnuceoiihirdihrghnsehsvghnthdrtghomheqnecuggftrfgrthhtvghrnhepge eghedugfduuddvleehheetgeeltdetieevuefhffevkefhveeufeeiieejgedvnecuvehl uhhsthgvrhfuihiivgepvdenucfrrghrrghmpehmrghilhhfrhhomhepiihirdihrghnse hsvghnthdrtghomh X-ME-Proxy: Feedback-ID: iccd040f4:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Mon, 3 Apr 2023 16:19:07 -0400 (EDT) From: Zi Yan To: "Matthew Wilcox (Oracle)" , Yang Shi , Yu Zhao , linux-mm@kvack.org Cc: Zi Yan , "Kirill A . Shutemov" , Ryan Roberts , =?utf-8?q?Michal_Koutn=C3=BD?= , Roman Gushchin , "Zach O'Keefe" , Andrew Morton , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH v3 6/7] mm: truncate: split huge page cache page to a non-zero order if possible. Date: Mon, 3 Apr 2023 16:18:38 -0400 Message-Id: <20230403201839.4097845-7-zi.yan@sent.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230403201839.4097845-1-zi.yan@sent.com> References: <20230403201839.4097845-1-zi.yan@sent.com> Reply-To: Zi Yan MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org From: Zi Yan To minimize the number of pages after a huge page truncation, we do not need to split it all the way down to order-0. The huge page has at most three parts, the part before offset, the part to be truncated, the part remaining at the end. Find the greatest common divisor of them to calculate the new page order from it, so we can split the huge page to this order and keep the remaining pages as large and as few as possible. Signed-off-by: Zi Yan --- mm/truncate.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/mm/truncate.c b/mm/truncate.c index 86de31ed4d32..817efd5e94b4 100644 --- a/mm/truncate.c +++ b/mm/truncate.c @@ -22,6 +22,7 @@ #include /* grr. try_to_release_page */ #include #include +#include #include "internal.h" /* @@ -211,7 +212,8 @@ int truncate_inode_folio(struct address_space *mapping, struct folio *folio) bool truncate_inode_partial_folio(struct folio *folio, loff_t start, loff_t end) { loff_t pos = folio_pos(folio); - unsigned int offset, length; + unsigned int offset, length, remaining; + unsigned int new_order = folio_order(folio); if (pos < start) offset = start - pos; @@ -222,6 +224,7 @@ bool truncate_inode_partial_folio(struct folio *folio, loff_t start, loff_t end) length = length - offset; else length = end + 1 - pos - offset; + remaining = folio_size(folio) - offset - length; folio_wait_writeback(folio); if (length == folio_size(folio)) { @@ -236,11 +239,25 @@ bool truncate_inode_partial_folio(struct folio *folio, loff_t start, loff_t end) */ folio_zero_range(folio, offset, length); + /* + * Use the greatest common divisor of offset, length, and remaining + * as the smallest page size and compute the new order from it. So we + * can truncate a subpage as large as possible. Round up gcd to + * PAGE_SIZE, otherwise ilog2 can give -1 when gcd/PAGE_SIZE is 0. + */ + new_order = ilog2(round_up(gcd(gcd(offset, length), remaining), + PAGE_SIZE) / PAGE_SIZE); + + /* order-1 THP not supported, downgrade to order-0 */ + if (new_order == 1) + new_order = 0; + + if (folio_has_private(folio)) folio_invalidate(folio, offset, length); if (!folio_test_large(folio)) return true; - if (split_folio(folio) == 0) + if (split_huge_page_to_list_to_order(&folio->page, NULL, new_order) == 0) return true; if (folio_test_dirty(folio)) return false;