From patchwork Tue Mar 21 00:48:28 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zi Yan X-Patchwork-Id: 13182059 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 B0172C7618D for ; Tue, 21 Mar 2023 00:49:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229842AbjCUAtB (ORCPT ); Mon, 20 Mar 2023 20:49:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56624 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229606AbjCUAs4 (ORCPT ); Mon, 20 Mar 2023 20:48:56 -0400 Received: from out2-smtp.messagingengine.com (out2-smtp.messagingengine.com [66.111.4.26]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E80DA19C42; Mon, 20 Mar 2023 17:48:53 -0700 (PDT) Received: from compute5.internal (compute5.nyi.internal [10.202.2.45]) by mailout.nyi.internal (Postfix) with ESMTP id 454555C005B; Mon, 20 Mar 2023 20:48:52 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute5.internal (MEProxy); Mon, 20 Mar 2023 20:48:52 -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= 1679359732; x=1679446132; bh=n0I3rKbVmW11Ko5MdyrWnLEXy5CTcBBnWUT tQZPt4TU=; b=TGOw0K2al2eY7sLD74hzDSD2ANtWUXGox+zhPeiE6P/ZNRvUeRK 4Q0E1OSDty/ycWijhLtITpkdOGOarjXiu5fjbrQ3nWDAN+QJGLTONr+uF1Q2Uc3l Q48w6zo1cQIsT1e/iFjfwnL9rPqppkTFZZ8DR7FAaqythtnQqFWf28twSJ818+pW MxoA8/Q1YQGKfE+sRpYG00S3FtH6s2dn1TImcA2bdwUMcy6TSJlcyjawq5pX/rXG byesOejoHcwfGEod9ItRRpSOFSr+WvxW7oMQjUxOh8TFlU0NGfbDID/+AwGhAJyS kP7Shwv+niUFBCz3C7lngIgEvcg9nOfO/FQ== 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= 1679359732; x=1679446132; bh=n0I3rKbVmW11Ko5MdyrWnLEXy5CTcBBnWUT tQZPt4TU=; b=VLrp8OERc6ago/IJ0cIfqE5ueb4bd17BUSOXX+/PiCWaLJcJjyd Su89Z+er3PRdhytvTZUnnTTXLq2pxmHZaKWGlhXwDW/j8avGXV1RqvqPsCbJA5LR XaSrQJ/kltnPp88OMBoTfnEq4ZIDTD4Uk3aHbzEs18a8DGB4ky8tc5tH+QiWV8ks fUSY5GIBk0XfQhIXNIqUOfjkUN+uNz58xYJ4r/9dJha7JCRfeHJ4UP1FQnRI4U86 Tq+yJY7w7c05XSu+4+cpgPEXo9L9Kn2oCE15QcC/RtukdTvDwenI6RmJuxwC80/c zrT0gjqbKoA6/aoyfrG4NIkliT0oM4AxUgQ== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvhedrvdefledgvdegucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhephffvvefufffkofgjfhhrggfgsedtqhertdertddtnecuhfhrohhmpegkihcu jggrnhcuoeiiihdrhigrnhesshgvnhhtrdgtohhmqeenucggtffrrghtthgvrhhnpeegge ehudfgudduvdelheehteegledtteeiveeuhfffveekhfevueefieeijeegvdenucevlhhu shhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpeiiihdrhigrnhessh gvnhhtrdgtohhm X-ME-Proxy: Feedback-ID: iccd040f4:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Mon, 20 Mar 2023 20:48:51 -0400 (EDT) From: Zi Yan To: "Matthew Wilcox (Oracle)" , Yang Shi , Yu Zhao , linux-mm@kvack.org Cc: Zi Yan , Andrew Morton , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH 4/5] mm: truncate: split huge page cache page to a non-zero order if possible. Date: Mon, 20 Mar 2023 20:48:28 -0400 Message-Id: <20230321004829.2012847-5-zi.yan@sent.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230321004829.2012847-1-zi.yan@sent.com> References: <20230321004829.2012847-1-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;