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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS autolearn=no 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 44893C433ED for ; Tue, 11 May 2021 22:20:27 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7B582616EA for ; Tue, 11 May 2021 22:20:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7B582616EA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4Ffsn504vZz3099 for ; Wed, 12 May 2021 08:20:25 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=linux-foundation.org header.i=@linux-foundation.org header.a=rsa-sha256 header.s=korg header.b=QMpcQYIa; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux-foundation.org (client-ip=198.145.29.99; helo=mail.kernel.org; envelope-from=akpm@linux-foundation.org; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=linux-foundation.org header.i=@linux-foundation.org header.a=rsa-sha256 header.s=korg header.b=QMpcQYIa; dkim-atps=neutral Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4FfsmV5M6Zz2xvT for ; Wed, 12 May 2021 08:19:53 +1000 (AEST) Received: by mail.kernel.org (Postfix) with ESMTPSA id E09EE6191C; Tue, 11 May 2021 22:19:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1620771590; bh=gUkAmwj67gu1MoY25mVV7c00HYZC1NsG64HkCPKMRjo=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=QMpcQYIa7jhYD11gnxYHT8+usShMP4wUKWzUC30NTAoG2IFH+31urgKSWas62Nh+S IyrIbCG+G6iizwaxetSWRSPThfSA2bK8dK8z/b9666rUK7NvK54X5lF6tXpzBildoq 1O6gHu/YRI6rj90h2BX/IvxBt+EFN8XoX2mA5bOw= Date: Tue, 11 May 2021 15:19:49 -0700 From: Andrew Morton To: "Aneesh Kumar K.V" Subject: Re: [PATCH v5 9/9] powerpc/mm: Enable move pmd/pud Message-Id: <20210511151949.fa1973124f3aba1ea7abceb9@linux-foundation.org> In-Reply-To: <20210422054323.150993-10-aneesh.kumar@linux.ibm.com> References: <20210422054323.150993-1-aneesh.kumar@linux.ibm.com> <20210422054323.150993-10-aneesh.kumar@linux.ibm.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: npiggin@gmail.com, linux-mm@kvack.org, kaleshsingh@google.com, joel@joelfernandes.org, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, 22 Apr 2021 11:13:23 +0530 "Aneesh Kumar K.V" wrote: > mremap HAVE_MOVE_PMD/PUD optimization time comparison for 1GB region: > 1GB mremap - Source PTE-aligned, Destination PTE-aligned > mremap time: 1127034ns > 1GB mremap - Source PMD-aligned, Destination PMD-aligned > mremap time: 508817ns > 1GB mremap - Source PUD-aligned, Destination PUD-aligned > mremap time: 23046ns Well that's nice. How significant is this in practice? How common is it for applications to successfully align the region? Do real-world applications actually benefit from this? Are there userspace libraries (malloc() etc) which should be reworked to fully exploit this?