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mx.microsoft.com 1; spf=pass smtp.mailfrom=nutanix.com; dmarc=pass action=none header.from=nutanix.com; dkim=pass header.d=nutanix.com; arc=none Received: from BL0PR02MB5601.namprd02.prod.outlook.com (2603:10b6:208:88::10) by BL0PR02MB4610.namprd02.prod.outlook.com (2603:10b6:208:4b::30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2793.17; Wed, 11 Mar 2020 17:45:58 +0000 Received: from BL0PR02MB5601.namprd02.prod.outlook.com ([fe80::ddf8:e6cc:908f:a98c]) by BL0PR02MB5601.namprd02.prod.outlook.com ([fe80::ddf8:e6cc:908f:a98c%6]) with mapi id 15.20.2814.007; Wed, 11 Mar 2020 17:45:58 +0000 From: Ivan Teterevkov CC: "corbet@lwn.net" , "akpm@linux-foundation.org" , "mchehab+samsung@kernel.org" , "tglx@linutronix.de" , "jpoimboe@redhat.com" , "pawan.kumar.gupta@linux.intel.com" , "jgross@suse.com" , "oneukum@suse.com" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , Ivan Teterevkov Subject: [PATCH] mm/vmscan: add vm_swappiness configuration knobs Thread-Topic: [PATCH] mm/vmscan: add vm_swappiness configuration knobs Thread-Index: AdX3zHNqbuFpQvKERxyPueA21j6FDg== Date: Wed, 11 Mar 2020 17:45:58 +0000 Message-ID: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [62.254.189.133] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: a175d3c5-408f-41b9-dd49-08d7c5e40ec0 x-ms-traffictypediagnostic: BL0PR02MB4610: x-ms-exchange-transport-forked: True x-microsoft-antispam-prvs: x-proofpoint-crosstenant: true x-ms-oob-tlc-oobclassifiers: OLM:10000; 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charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: nutanix.com X-MS-Exchange-CrossTenant-Network-Message-Id: a175d3c5-408f-41b9-dd49-08d7c5e40ec0 X-MS-Exchange-CrossTenant-originalarrivaltime: 11 Mar 2020 17:45:58.5551 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: bb047546-786f-4de1-bd75-24e5b6f79043 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: ZP+5xltUGXBirbgVYOH7rvFy6hApq2hQUnVGd3OlR+ZyTaoVFhxvmA4edyOsTqeK85c+PWNwnaWzEvAvnLZE0D3t8teFyqT15LuWHnbA+OU= X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL0PR02MB4610 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.572 definitions=2020-03-11_07:2020-03-11,2020-03-11 signatures=0 X-Proofpoint-Spam-Reason: safe To: unlisted-recipients:; (no To-header on input) Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org This patch adds a couple of knobs: - The configuration option (CONFIG_VM_SWAPPINESS). - The command line parameter (vm_swappiness). The default value is preserved, but now defined by CONFIG_VM_SWAPPINESS. Historically, the default swappiness is set to the well-known value 60, and this works well for the majority of cases. The vm_swappiness is also exposed as the kernel parameter that can be changed at runtime too, e.g. with sysctl. This approach might not suit well some configurations, e.g. systemd-based distros, where systemd is put in charge of the cgroup controllers, including the memory one. In such cases, the default swappiness 60 is copied across the cgroup subtrees early at startup, when systemd is arranging the slices for its services, before the sysctl.conf or tmpfiles.d/*.conf changes are applied. One could run a script to traverse the cgroup trees later and set the desired memory.swappiness individually in each occurrence when the runtime is set up, but this would require some amount of work to implement properly. Instead, why not set the default swappiness as early as possible? Signed-off-by: Ivan Teterevkov --- .../admin-guide/kernel-parameters.txt | 4 ++++ mm/Kconfig | 10 ++++++++ mm/vmscan.c | 24 ++++++++++++++++++- 3 files changed, 37 insertions(+), 1 deletion(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentatio= n/admin-guide/kernel-parameters.txt index c07815d230bc..5d54a4303522 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -5317,6 +5317,10 @@ P Enable page structure init time poisoning - Disable all of the above options =20 + vm_swappiness=3D [KNL] + Sets the default vm_swappiness. + Ranges from 0 to 100, the default value is 60. + vmalloc=3Dnn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact size of . This can be used to increase the minimum size (128MB on x86). It can also be used to diff --git a/mm/Kco= nfig b/mm/Kconfig index ab80933be65f..ec59c19e578e 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -739,4 +739,14 @@ config ARCH_HAS_HUGEPD config MAPPING_DIRTY_HELPERS bool =20 +config VM_SWAPPINESS + int "Default memory swappiness" + default 60 + range 0 100 + help + Sets the default vm_swappiness, that could be changed later + in the runtime, e.g. kernel command line, sysctl, etc. + + Higher value means more swappy. Historically, defaults to 60. + endmenu diff --git a/mm/vmscan.c b/mm/vmscan.c index 876370565455..7d2d3550f698 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -163,7 +163,29 @@ struct scan_control { /* * From 0 .. 100. Higher means more swappy. */ -int vm_swappiness =3D 60; +int vm_swappiness =3D CONFIG_VM_SWAPPINESS; + +static int __init swappiness_cmdline(char *str) { + int val, err; + + if (!str) + return -EINVAL; + + err =3D kstrtoint(str, 10, &val); + if (err) + return -EINVAL; + + if (val < 0 || val > 100) + return -EINVAL; + + vm_swappiness =3D val; + + return 0; +} + +early_param("vm_swappiness", swappiness_cmdline); + /* * The total number of pages which are beyond the high watermark within al= l * zones. -- 2.25.0