From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 1C7C826A0C7 for ; Mon, 28 Apr 2025 12:52:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745844733; cv=none; b=Ad9Zkqxrtj1jAG3FAyPCIpctDf0VRR62D3GkKcpfZMQfBfsA3EINgBiHGDTQwXYPanXDL0X7u22RvSqC+bK1K5Tq70S8oyLPf3AYbZxjp0KIih1m1N8Id0EHJ9C1I9PZCsmqR9MYVD+cULAffTtaHmblyNO/SCcH1KmI8W6CY4I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745844733; c=relaxed/simple; bh=tS9gBtlQAJ+wmgXscJ7SZZqo4CjovXoIb4pNEH4cLhI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=kZ9vuoltSofCiTf/6kJwewyMaMaYU8OboljB+scsiN7EqBLRn/FNBwSVN4h3f5NB5lzBZvNUup1zYpHWQ3ZAJIJAASbuH2w581hbvDoy0zSAEdjut2Q3uuckWRv3lzazdl7tRY+KvmZVldwMta1/ds7hOL9K+ZvUXfNudfNbkr4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com 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 E44D01516; Mon, 28 Apr 2025 05:52:04 -0700 (PDT) Received: from [10.163.78.210] (unknown [10.163.78.210]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 680863F673; Mon, 28 Apr 2025 05:52:03 -0700 (PDT) Message-ID: <72b0be04-73d5-49e3-8e35-c8999e37fd58@arm.com> Date: Mon, 28 Apr 2025 18:22:00 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/7] Optimize mprotect for large folios To: akpm@linux-foundation.org Cc: ryan.roberts@arm.com, 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, namit@vmware.com, hughd@google.com, yang@os.amperecomputing.com, ziy@nvidia.com References: <20250428120414.12101-1-dev.jain@arm.com> Content-Language: en-US From: Dev Jain In-Reply-To: <20250428120414.12101-1-dev.jain@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 28/04/25 5:34 pm, Dev Jain wrote: > This patchset optimizes the mprotect() system call for large folios > by PTE-batching. > > 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: 4.2 seconds > > 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 276% performance improvement. Messed up the denominator, I mean ((7.9 - 2.1) / 7.9) * 100 = 73%. > > Dev Jain (7): > mm: Refactor code in mprotect > mm: Optimize mprotect() by batch-skipping PTEs > mm: Add batched versions of ptep_modify_prot_start/commit > arm64: Add batched version of ptep_modify_prot_start > arm64: Add batched version of ptep_modify_prot_commit > mm: Batch around can_change_pte_writable() > mm: Optimize mprotect() through PTE-batching > > arch/arm64/include/asm/pgtable.h | 10 ++ > arch/arm64/mm/mmu.c | 21 +++- > include/linux/mm.h | 4 +- > include/linux/pgtable.h | 42 ++++++++ > mm/gup.c | 2 +- > mm/huge_memory.c | 4 +- > mm/memory.c | 6 +- > mm/mprotect.c | 163 +++++++++++++++++++++---------- > mm/pgtable-generic.c | 16 ++- > 9 files changed, 198 insertions(+), 70 deletions(-) >