From patchwork Fri Apr 9 18:50:38 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 12194839 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=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 DF57DC433B4 for ; Fri, 9 Apr 2021 18:52:35 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7E5766113A for ; Fri, 9 Apr 2021 18:52:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7E5766113A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id E29FD6B006E; Fri, 9 Apr 2021 14:52:34 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DB31E6B0070; Fri, 9 Apr 2021 14:52:34 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BB92F6B0071; Fri, 9 Apr 2021 14:52:34 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0165.hostedemail.com [216.40.44.165]) by kanga.kvack.org (Postfix) with ESMTP id 971EC6B006E for ; Fri, 9 Apr 2021 14:52:34 -0400 (EDT) Received: from smtpin12.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 5A1CEBEF2 for ; Fri, 9 Apr 2021 18:52:34 +0000 (UTC) X-FDA: 78013724628.12.CAFE6DF Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf07.hostedemail.com (Postfix) with ESMTP id CB1E9A000145 for ; Fri, 9 Apr 2021 18:52:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=k9UQJrroA7+b5FsVn9SgeyEPUnOcRSZz/F33X7W870c=; b=emxCeTdgjw5mMIOnmcPfDWAMPj coxh6Q90VA8KO3R63jZ+MYkpUByZBFAzLQG53eLmuxPvmU03KdwerAgLkZEtfNLlCCCSRC+i6RtDj hdpDnn8EJ6m7XeVoGxtM2maZRKFHY4QBb+wz9jjfEOOt8MKv1yO8ShOFVezPb5Y/xtpzCRHkfEzoR SKwX/trgOG1l6OAif3RRHAql0D1LI3hKlGPSuPW0f+yBny6g0gXCU104zvRilfepSVMaP48iehlxm 0OPCjxQjjltLtLqlYAXgQ5bIightYT4JbGazmQA4lFzThe3/PrKqkEdP/Kymlpw3YspI6LcWHjtcJ KeJZXOpg==; Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1lUwEA-000n0R-Q0; Fri, 09 Apr 2021 18:51:40 +0000 From: "Matthew Wilcox (Oracle)" To: linux-mm@kvack.org Cc: "Matthew Wilcox (Oracle)" , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-cachefs@redhat.com, linux-afs@lists.infradead.org Subject: [PATCH v7 01/28] mm: Optimise nth_page for contiguous memmap Date: Fri, 9 Apr 2021 19:50:38 +0100 Message-Id: <20210409185105.188284-2-willy@infradead.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210409185105.188284-1-willy@infradead.org> References: <20210409185105.188284-1-willy@infradead.org> MIME-Version: 1.0 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: CB1E9A000145 X-Stat-Signature: s79szzsfze5ioio3txgw9uataey1a9yd Received-SPF: none (infradead.org>: No applicable sender policy available) receiver=imf07; identity=mailfrom; envelope-from=""; helo=casper.infradead.org; client-ip=90.155.50.34 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1617994353-127303 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: If the memmap is virtually contiguous (either because we're using a virtually mapped memmap or because we don't support a discontig memmap at all), then we can implement nth_page() by simple addition. Contrary to popular belief, the compiler is not able to optimise this itself for a vmemmap configuration. This reduces one example user (sg.c) by four instructions: struct page *page = nth_page(rsv_schp->pages[k], offset >> PAGE_SHIFT); before: 49 8b 45 70 mov 0x70(%r13),%rax 48 63 c9 movslq %ecx,%rcx 48 c1 eb 0c shr $0xc,%rbx 48 8b 04 c8 mov (%rax,%rcx,8),%rax 48 2b 05 00 00 00 00 sub 0x0(%rip),%rax R_X86_64_PC32 vmemmap_base-0x4 48 c1 f8 06 sar $0x6,%rax 48 01 d8 add %rbx,%rax 48 c1 e0 06 shl $0x6,%rax 48 03 05 00 00 00 00 add 0x0(%rip),%rax R_X86_64_PC32 vmemmap_base-0x4 after: 49 8b 45 70 mov 0x70(%r13),%rax 48 63 c9 movslq %ecx,%rcx 48 c1 eb 0c shr $0xc,%rbx 48 c1 e3 06 shl $0x6,%rbx 48 03 1c c8 add (%rax,%rcx,8),%rbx Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Christoph Hellwig --- include/linux/mm.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index b58c73e50da0..036f63a44a5c 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -234,7 +234,11 @@ int overcommit_policy_handler(struct ctl_table *, int, void *, size_t *, int __add_to_page_cache_locked(struct page *page, struct address_space *mapping, pgoff_t index, gfp_t gfp, void **shadowp); +#if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP) #define nth_page(page,n) pfn_to_page(page_to_pfn((page)) + (n)) +#else +#define nth_page(page,n) ((page) + (n)) +#endif /* to align the pointer to the (next) page boundary */ #define PAGE_ALIGN(addr) ALIGN(addr, PAGE_SIZE)