From patchwork Tue Apr 17 14:33:07 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laurent Dufour X-Patchwork-Id: 899388 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 40QSnh07xnz9s0W for ; Wed, 18 Apr 2018 00:49:28 +1000 (AEST) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.vnet.ibm.com Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 40QSng5T1XzF200 for ; Wed, 18 Apr 2018 00:49:27 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.vnet.ibm.com X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Authentication-Results: lists.ozlabs.org; spf=none (mailfrom) smtp.mailfrom=linux.vnet.ibm.com (client-ip=148.163.158.5; helo=mx0a-001b2d01.pphosted.com; envelope-from=ldufour@linux.vnet.ibm.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.vnet.ibm.com Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (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 40QSRf6GFbzF1yf for ; Wed, 18 Apr 2018 00:33:50 +1000 (AEST) Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w3HESvUm041087 for ; Tue, 17 Apr 2018 10:33:48 -0400 Received: from e06smtp13.uk.ibm.com (e06smtp13.uk.ibm.com [195.75.94.109]) by mx0a-001b2d01.pphosted.com with ESMTP id 2hdj4ptnw7-1 (version=TLSv1.2 cipher=AES256-SHA256 bits=256 verify=NOT) for ; Tue, 17 Apr 2018 10:33:48 -0400 Received: from localhost by e06smtp13.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Tue, 17 Apr 2018 15:33:37 +0100 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w3HEXbiv56557612; Tue, 17 Apr 2018 14:33:37 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id EA8ACA4055; Tue, 17 Apr 2018 15:25:45 +0100 (BST) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C896EA4040; Tue, 17 Apr 2018 15:25:43 +0100 (BST) Received: from nimbus.lab.toulouse-stg.fr.ibm.com (unknown [9.145.171.143]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 17 Apr 2018 15:25:43 +0100 (BST) From: Laurent Dufour To: akpm@linux-foundation.org, mhocko@kernel.org, peterz@infradead.org, kirill@shutemov.name, ak@linux.intel.com, dave@stgolabs.net, jack@suse.cz, Matthew Wilcox , benh@kernel.crashing.org, mpe@ellerman.id.au, paulus@samba.org, Thomas Gleixner , Ingo Molnar , hpa@zytor.com, Will Deacon , Sergey Senozhatsky , Andrea Arcangeli , Alexei Starovoitov , kemi.wang@intel.com, sergey.senozhatsky.work@gmail.com, Daniel Jordan , David Rientjes , Jerome Glisse , Ganesh Mahendran Subject: [PATCH v10 01/25] mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT Date: Tue, 17 Apr 2018 16:33:07 +0200 X-Mailer: git-send-email 2.7.4 In-Reply-To: <1523975611-15978-1-git-send-email-ldufour@linux.vnet.ibm.com> References: <1523975611-15978-1-git-send-email-ldufour@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18041714-0012-0000-0000-000005CBDCCC X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18041714-0013-0000-0000-000019482804 Message-Id: <1523975611-15978-2-git-send-email-ldufour@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2018-04-17_07:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1804170131 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org, npiggin@gmail.com, linux-mm@kvack.org, paulmck@linux.vnet.ibm.com, Tim Chen , haren@linux.vnet.ibm.com, khandual@linux.vnet.ibm.com Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" This configuration variable will be used to build the code needed to handle speculative page fault. By default it is turned off, and activated depending on architecture support, SMP and MMU. Suggested-by: Thomas Gleixner Suggested-by: David Rientjes Signed-off-by: Laurent Dufour --- mm/Kconfig | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/mm/Kconfig b/mm/Kconfig index d5004d82a1d6..5484dca11199 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -752,3 +752,25 @@ config GUP_BENCHMARK performance of get_user_pages_fast(). See tools/testing/selftests/vm/gup_benchmark.c + +config ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT + def_bool n + +config SPECULATIVE_PAGE_FAULT + bool "Speculative page faults" + default y + depends on ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT + depends on MMU && SMP + help + Try to handle user space page faults without holding the mmap_sem. + + This should allow better concurrency for massively threaded process + since the page fault handler will not wait for other threads memory + layout change to be done, assuming that this change is done in another + part of the process's memory space. This type of page fault is named + speculative page fault. + + If the speculative page fault fails because of a concurrency is + detected or because underlying PMD or PTE tables are not yet + allocating, it is failing its processing and a classic page fault + is then tried.