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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7AF41C7EE39 for ; Mon, 30 Jun 2025 11:18:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Q4ZKConExH9t+sZf4SwZM6mks80+wm+m2CJUcgWA0BA=; b=0yzpvcbv972QEQPuWg7f/pCjIP 1HlowmQ9Bo/k7CfnGCeo7IK4myVdOV68FQhsWg3KgbaDO7UMDnwIvrvlhO/v5iJd/od5fh9/6jWgZ 7/GMuP/CRB6cgsJ5BtjxnD7izXFGfMGqjdt/mmyPKKksi76yzm+v/mqbBLrPxvB/cbfRmT2fKUhoc bl/0Ez38eHsJujKEudpR/yx4dsHjxn9IEQTV+SW2lXqrp5bEp5uSn8XaLXszBerYP2njKHmAM3HR3 +bc2BWH7vFwqRv+a/50af2V0LA3tmF1pB2lqq7KNfvWu4ohYIxArKCZzxZt5eCPlgq4kOvOJbmIK4 7SKWrw2g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uWCWv-00000001zv0-0pBy; Mon, 30 Jun 2025 11:18:33 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uWC1N-00000001w5J-0THx for linux-arm-kernel@lists.infradead.org; Mon, 30 Jun 2025 10:45:58 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B8E0B1F60; Mon, 30 Jun 2025 03:45:40 -0700 (PDT) Received: from [10.1.34.165] (XHFQ2J9959.cambridge.arm.com [10.1.34.165]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A96E03F58B; Mon, 30 Jun 2025 03:45:52 -0700 (PDT) Message-ID: <7eaee53b-d538-4991-addd-379a380b8ee2@arm.com> Date: Mon, 30 Jun 2025 11:45:50 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 0/4] Optimize mprotect() for large folios Content-Language: en-GB To: Dev Jain , Andrew Morton Cc: david@redhat.com, willy@infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, will@kernel.org, Liam.Howlett@oracle.com, lorenzo.stoakes@oracle.com, vbabka@suse.cz, jannh@google.com, anshuman.khandual@arm.com, peterx@redhat.com, joey.gouly@arm.com, ioworker0@gmail.com, baohua@kernel.org, kevin.brodsky@arm.com, quic_zhenhuah@quicinc.com, christophe.leroy@csgroup.eu, yangyicong@hisilicon.com, linux-arm-kernel@lists.infradead.org, hughd@google.com, yang@os.amperecomputing.com, ziy@nvidia.com References: <20250628113435.46678-1-dev.jain@arm.com> <20250629160549.da922e78d202c510a1ec68f8@linux-foundation.org> <29f418be-31c4-47b0-bcac-3375f57d00e7@arm.com> From: Ryan Roberts In-Reply-To: <29f418be-31c4-47b0-bcac-3375f57d00e7@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250630_034557_190563_D366B2A1 X-CRM114-Status: GOOD ( 10.09 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 30/06/2025 04:33, Dev Jain wrote: > > On 30/06/25 4:35 am, Andrew Morton wrote: >> On Sat, 28 Jun 2025 17:04:31 +0530 Dev Jain wrote: >> >>> This patchset optimizes the mprotect() system call for large folios >>> by PTE-batching. No issues were observed with mm-selftests, build >>> tested on x86_64. >> um what.  Seems to claim that "selftests still compiles after I messed >> with stuff", which isn't very impressive ;)  Please clarify? > > Sorry I mean to say that the mm-selftests pass. I think you're saying you both compiled and ran the mm selftests for arm64. And additionally you compiled for x86_64? (Just trying to help clarify). > >> >>> We use the following test cases to measure performance, mprotect()'ing >>> the mapped memory to read-only then read-write 40 times: >>> >>> Test case 1: Mapping 1G of memory, touching it to get PMD-THPs, then >>> pte-mapping those THPs >>> Test case 2: Mapping 1G of memory with 64K mTHPs >>> Test case 3: Mapping 1G of memory with 4K pages >>> >>> Average execution time on arm64, Apple M3: >>> Before the patchset: >>> T1: 7.9 seconds   T2: 7.9 seconds   T3: 4.2 seconds >>> >>> After the patchset: >>> T1: 2.1 seconds   T2: 2.2 seconds   T3: 4.3 seconds >> Well that's tasty. >> >>> Observing T1/T2 and T3 before the patchset, we also remove the regression >>> introduced by ptep_get() on a contpte block. And, for large folios we get >>> an almost 74% performance improvement, albeit the trade-off being a slight >>> degradation in the small folio case. >>>