From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-5.8 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 469207DD31 for ; Tue, 24 Apr 2018 06:41:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755909AbeDXGl5 (ORCPT ); Tue, 24 Apr 2018 02:41:57 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:34686 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755999AbeDXGku (ORCPT ); Tue, 24 Apr 2018 02:40:50 -0400 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 w3O6d5NJ038753 for ; Tue, 24 Apr 2018 02:40:50 -0400 Received: from e06smtp14.uk.ibm.com (e06smtp14.uk.ibm.com [195.75.94.110]) by mx0a-001b2d01.pphosted.com with ESMTP id 2hhy9y8ncg-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 24 Apr 2018 02:40:50 -0400 Received: from localhost by e06smtp14.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Tue, 24 Apr 2018 07:40:44 +0100 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w3O6eixP66257000; Tue, 24 Apr 2018 06:40:44 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B9428AE059; Tue, 24 Apr 2018 07:30:27 +0100 (BST) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3643EAE056; Tue, 24 Apr 2018 07:30:26 +0100 (BST) Received: from rapoport-lnx (unknown [9.148.8.99]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Tue, 24 Apr 2018 07:30:26 +0100 (BST) Received: by rapoport-lnx (sSMTP sendmail emulation); Tue, 24 Apr 2018 09:40:42 +0300 From: Mike Rapoport To: Jonathan Corbet Cc: Andrew Morton , Andrea Arcangeli , linux-doc , linux-mm , lkml , Mike Rapoport Subject: [PATCH 6/7] docs/vm: ksm: udpate description of stable_node_{dups,chains} Date: Tue, 24 Apr 2018 09:40:27 +0300 X-Mailer: git-send-email 2.7.4 In-Reply-To: <1524552028-7017-1-git-send-email-rppt@linux.vnet.ibm.com> References: <1524552028-7017-1-git-send-email-rppt@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18042406-0044-0000-0000-0000054B71A1 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18042406-0045-0000-0000-0000288BA327 Message-Id: <1524552028-7017-7-git-send-email-rppt@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-04-24_01:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=2 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-1804240067 Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org Remove implementation details from sysfs parameter descriptions. Also move the paragraph discussing fragmentation issues and their possible solution to the "Design" section. Signed-off-by: Mike Rapoport --- Documentation/vm/ksm.rst | 21 ++++++++++----------- 1 file changed, 10 insertions(+), 11 deletions(-) diff --git a/Documentation/vm/ksm.rst b/Documentation/vm/ksm.rst index 18d7c71..afcf5a8 100644 --- a/Documentation/vm/ksm.rst +++ b/Documentation/vm/ksm.rst @@ -170,10 +170,9 @@ pages_volatile full_scans how many times all mergeable areas have been scanned stable_node_chains - number of stable node chains allocated, this is effectively the number of KSM pages that hit the ``max_page_sharing`` limit stable_node_dups - number of stable node dups queued into the stable_node chains + number of duplicated KSM pages A high ratio of ``pages_sharing`` to ``pages_shared`` indicates good sharing, but a high ratio of ``pages_unshared`` to ``pages_sharing`` @@ -185,15 +184,6 @@ The maximum possible ``pages_sharing/pages_shared`` ratio is limited by the ``max_page_sharing`` tunable. To increase the ratio ``max_page_sharing`` must be increased accordingly. -The ``stable_node_dups/stable_node_chains`` ratio is also affected by the -``max_page_sharing`` tunable, and an high ratio may indicate fragmentation -in the stable_node dups, which could be solved by introducing -fragmentation algorithms in ksmd which would refile rmap_items from -one stable_node dup to another stable_node dup, in order to free up -stable_node "dups" with few rmap_items in them, but that may increase -the ksmd CPU usage and possibly slowdown the readonly computations on -the KSM pages of the applications. - Design ====== @@ -247,6 +237,15 @@ deduplication factor at the expense of slower worst case for rmap walks for any KSM page which can happen during swapping, compaction, NUMA balancing and page migration. +The ``stable_node_dups/stable_node_chains`` ratio is also affected by the +``max_page_sharing`` tunable, and an high ratio may indicate fragmentation +in the stable_node dups, which could be solved by introducing +fragmentation algorithms in ksmd which would refile rmap_items from +one stable_node dup to another stable_node dup, in order to free up +stable_node "dups" with few rmap_items in them, but that may increase +the ksmd CPU usage and possibly slowdown the readonly computations on +the KSM pages of the applications. + The whole list of stable_node "dups" linked in the stable_node "chains" is scanned periodically in order to prune stale stable_nodes. The frequency of such scans is defined by -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html