From patchwork Thu Apr 25 10:35:31 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mike Rapoport X-Patchwork-Id: 1066682 Return-Path: Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A6381C282E1 for ; Thu, 25 Apr 2019 10:35:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7B3762084B for ; Thu, 25 Apr 2019 10:35:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730416AbfDYKfo (ORCPT ); Thu, 25 Apr 2019 06:35:44 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:52228 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730384AbfDYKfo (ORCPT ); Thu, 25 Apr 2019 06:35:44 -0400 Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x3PAJQGx109726 for ; Thu, 25 Apr 2019 06:35:42 -0400 Received: from e06smtp03.uk.ibm.com (e06smtp03.uk.ibm.com [195.75.94.99]) by mx0a-001b2d01.pphosted.com with ESMTP id 2s3ach2ag4-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 25 Apr 2019 06:35:42 -0400 Received: from localhost by e06smtp03.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Thu, 25 Apr 2019 11:35:37 +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 x3PAZahC49676394 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 25 Apr 2019 10:35:36 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 05C94A4059; Thu, 25 Apr 2019 10:35:36 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 85E66A4053; Thu, 25 Apr 2019 10:35:34 +0000 (GMT) Received: from rapoport-lnx (unknown [9.148.205.17]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Thu, 25 Apr 2019 10:35:34 +0000 (GMT) Received: by rapoport-lnx (sSMTP sendmail emulation); Thu, 25 Apr 2019 13:35:33 +0300 From: Mike Rapoport To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Rapoport Subject: [PATCH] mm/Kconfig: update "Memory Model" help text Date: Thu, 25 Apr 2019 13:35:31 +0300 X-Mailer: git-send-email 2.7.4 X-TM-AS-GCONF: 00 x-cbid: 19042510-0012-0000-0000-000003146FF6 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19042510-0013-0000-0000-0000214CC968 Message-Id: <1556188531-20728-1-git-send-email-rppt@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-04-25_09:,, 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 mlxscore=0 impostorscore=0 mlxlogscore=938 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904250067 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The help describing the memory model selection is outdated. It still says that SPARSEMEM is experimental and DISCONTIGMEM is a preferred over SPARSEMEM. Update the help text for the relevant options: * add a generic help for the "Memory Model" prompt * add description for FLATMEM * reduce the description of DISCONTIGMEM and add a deprecation note * prefer SPARSEMEM over DISCONTIGMEM Signed-off-by: Mike Rapoport Acked-by: Michal Hocko --- mm/Kconfig | 48 +++++++++++++++++++++++------------------------- 1 file changed, 23 insertions(+), 25 deletions(-) diff --git a/mm/Kconfig b/mm/Kconfig index 25c71eb8a7db..8f7ae4d71b77 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -11,23 +11,24 @@ choice default DISCONTIGMEM_MANUAL if ARCH_DISCONTIGMEM_DEFAULT default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT default FLATMEM_MANUAL + help + This option allows you to change some of the ways that + Linux manages its memory internally. Most users will + only have one option here selected by the architecture + configuration. This is normal. config FLATMEM_MANUAL bool "Flat Memory" depends on !(ARCH_DISCONTIGMEM_ENABLE || ARCH_SPARSEMEM_ENABLE) || ARCH_FLATMEM_ENABLE help - This option allows you to change some of the ways that - Linux manages its memory internally. Most users will - only have one option here: FLATMEM. This is normal - and a correct option. - - Some users of more advanced features like NUMA and - memory hotplug may have different options here. - DISCONTIGMEM is a more mature, better tested system, - but is incompatible with memory hotplug and may suffer - decreased performance over SPARSEMEM. If unsure between - "Sparse Memory" and "Discontiguous Memory", choose - "Discontiguous Memory". + This option is best suited for non-NUMA systems with + flat address space. The FLATMEM is the most efficient + system in terms of performance and resource consumption + and it is the best option for smaller systems. + + For systems that have holes in their physical address + spaces and for features like NUMA and memory hotplug, + choose "Sparse Memory" If unsure, choose this option (Flat Memory) over any other. @@ -38,29 +39,26 @@ config DISCONTIGMEM_MANUAL This option provides enhanced support for discontiguous memory systems, over FLATMEM. These systems have holes in their physical address spaces, and this option provides - more efficient handling of these holes. However, the vast - majority of hardware has quite flat address spaces, and - can have degraded performance from the extra overhead that - this option imposes. + more efficient handling of these holes. - Many NUMA configurations will have this as the only option. + Although "Discontiguous Memory" is still used by several + architectures, it is considered deprecated in favor of + "Sparse Memory". - If unsure, choose "Flat Memory" over this option. + If unsure, choose "Sparse Memory" over this option. config SPARSEMEM_MANUAL bool "Sparse Memory" depends on ARCH_SPARSEMEM_ENABLE help This will be the only option for some systems, including - memory hotplug systems. This is normal. + memory hot-plug systems. This is normal. - For many other systems, this will be an alternative to - "Discontiguous Memory". This option provides some potential - performance benefits, along with decreased code complexity, - but it is newer, and more experimental. + This option provides efficient support for systems with + holes is their physical address space and allows memory + hot-plug and hot-remove. - If unsure, choose "Discontiguous Memory" or "Flat Memory" - over this option. + If unsure, choose "Flat Memory" over this option. endchoice