From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9F953C4167D for ; Tue, 12 Dec 2023 13:46:35 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 395DD6B02E7; Tue, 12 Dec 2023 08:46:35 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 345736B02E9; Tue, 12 Dec 2023 08:46:35 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1C0506B02EA; Tue, 12 Dec 2023 08:46:35 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 081056B02E7 for ; Tue, 12 Dec 2023 08:46:35 -0500 (EST) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id CD3CBA09D1 for ; Tue, 12 Dec 2023 13:46:34 +0000 (UTC) X-FDA: 81558291108.10.8AED4F8 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf19.hostedemail.com (Postfix) with ESMTP id 6D88A1A0024 for ; Tue, 12 Dec 2023 13:46:32 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=A0Amt8gj; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf19.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1702388792; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=8DODWjUHEOXpo4jstEumop4gYxI3RMhCZ+EH7YA+W/g=; b=dbH7urq4QSbk8KzQn7ezOEeg+oOkS1Fw3BUywwZzfM4wCEu3k6+f8COiFoi9yKE6WoSBHT Dd0aI6F4zdL7B88nuz3guvNSPr1d01FM1q8ziikhPwRVy3MEZXCvCG1C5GPTRUsP1RcTwq js3X8xV2fKB/pSJK2XWHWkxyf3/ko8g= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=A0Amt8gj; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf19.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1702388792; a=rsa-sha256; cv=none; b=EnsSWmOugQMKrZ+T+Mw38cSmjlDN/0XDu/k0d8badIznaIIh6is+fySvMWx2M3CJhONuVa aWBw4BH+Nr4mbVNxrEdKUOLASXKUYPX6rArSpCW0o3a5xe0n/TfLL4+TgUh6t2kJP5kR0C 2qu1EyzOkCRfz1UVoB0t9CxqJWNrQRo= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1702388789; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=8DODWjUHEOXpo4jstEumop4gYxI3RMhCZ+EH7YA+W/g=; b=A0Amt8gjS7NbgDV0mTjSefIIR64o0/4IRLR+hL8oOXYyqHN0lvfnqzpNtndyp/HPkFeH1r wLu4R3YcO1CFDH1cxJN0C6+7Txkxl0lLdrIUo29qkWugg3N62EQcLAltZaUIdx5VmRoClA JAGLzkVuzxtGJ+f5AYGTrUpRGXQmSG8= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-330-tfISwCmMOM6Dman0eA8Ynw-1; Tue, 12 Dec 2023 08:46:26 -0500 X-MC-Unique: tfISwCmMOM6Dman0eA8Ynw-1 Received: by mail-wr1-f69.google.com with SMTP id ffacd0b85a97d-333501e22caso4648754f8f.2 for ; Tue, 12 Dec 2023 05:46:25 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1702388785; x=1702993585; h=content-transfer-encoding:in-reply-to:organization:autocrypt:from :references:cc:to:content-language:subject:user-agent:mime-version :date:message-id:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=8DODWjUHEOXpo4jstEumop4gYxI3RMhCZ+EH7YA+W/g=; b=sAcQFImmohtAkFiUjCDxemeHdsNqEsz09jOdYATurFC/ubFYwS/2IlWwQNgusRzgvG U1BGxKQ3E1GlNBOib4RNPWt8Y6pKawXSRvyc8UnMH4gVSF6ZprCdAFFPmC/fU6Nu0qte otpKlimdWPbxCLiP2qo9aeC+T4IGCkI6A7rFnFJwD7zQHZollIjJjN5q9Ow57GW6oU6N DBp0HOKMPPXQbLa7CKN1jsBwQRYoJLSGBTRlAquW7A090/b1PHYgBSea/Zf0X8QwW8lX aUsi4o7OH6pdK9gTo+YymUBGCOf/dJRoYnWrdvKc3OMmF5OhL6aYm1bfjzyA5hSmUAKY qcQw== X-Gm-Message-State: AOJu0Yyrf0I+CXiy0AOznDVwfdHcdhR8MOWRDCfYBfNp3mhNTzz3jLSa 8jbgvKHZFRd/8Xhh97XvdBZZJDUROswusBuhfQ5U9pe3bakMHnsdi0r5y+USwHqzZ1C9uD1/QBe PoF3HqEvsTZs= X-Received: by 2002:a5d:690b:0:b0:333:fd3:1a7f with SMTP id t11-20020a5d690b000000b003330fd31a7fmr3280230wru.52.1702388784962; Tue, 12 Dec 2023 05:46:24 -0800 (PST) X-Google-Smtp-Source: AGHT+IEPcAUkAnVXkT/RFK+r6/G570L2IwjrcW/StIsDaH6zBDs2G0l+T3BpbiPbTtwbrq4MMwYShA== X-Received: by 2002:a5d:690b:0:b0:333:fd3:1a7f with SMTP id t11-20020a5d690b000000b003330fd31a7fmr3280221wru.52.1702388784645; Tue, 12 Dec 2023 05:46:24 -0800 (PST) Received: from ?IPV6:2003:cb:c74b:ca00:4ca2:ff2c:9092:f070? (p200300cbc74bca004ca2ff2c9092f070.dip0.t-ipconnect.de. [2003:cb:c74b:ca00:4ca2:ff2c:9092:f070]) by smtp.gmail.com with ESMTPSA id e10-20020adffd0a000000b003334675634bsm10885476wrr.29.2023.12.12.05.46.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 12 Dec 2023 05:46:24 -0800 (PST) Message-ID: <525a4d9c-efaf-4663-a354-10f9e3ff2148@redhat.com> Date: Tue, 12 Dec 2023 14:46:23 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 4/4] mm/ksm: document ksm advisor and its sysfs knobs To: Stefan Roesch , kernel-team@fb.com Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, riel@surriel.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20231204234906.1237478-1-shr@devkernel.io> <20231204234906.1237478-5-shr@devkernel.io> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <20231204234906.1237478-5-shr@devkernel.io> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: f4skthnqefny48cw4zjqfxujesncd7ck X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 6D88A1A0024 X-HE-Tag: 1702388792-153570 X-HE-Meta: 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 fbUJet3O IkC1PrJtWFbZnKdruj0VzD4GB9olTTcwPa/PV9RkENNkzL0An3mzdTbRi60H/LrSPuKNp06BiGXKsr9+5zYj3hE+5kwdXfOM9v6BxjF+Pd/SxweDW3bzsPUXWiPo1kgvBmRend0+Lx++QQCbz/BW1+55J2t2fYnbaVgw8MXT8qE5sbO9oM3XSPD9mpsOZOyA5cZpwJCdvvhz4mNWLHDVG3nBM8rAP4w2246jlGbVB2ubivsY2xzj0s/mDIem+fr6afL16ILhKBKLZL27WsAxVxqVtfHzsvMrrippR4sF6cMt1CjItqBrRxXQp8cQJEoauCDdgH7jGAlOoMBWmAN0np0YrUbUDXnsmRu1SIx9a4EEtXFqXlvBX2O8112Ex0pAhegZ6LMHx8lGOwmhVBZlR0UtXiYgFSoPafo9x1ykpl25JcC/XIFKrGonKFJa0Yo6CaQWj X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 05.12.23 00:49, Stefan Roesch wrote: > This documents the KSM advisor and its new knobs in /sys/fs/kernel/mm. > > Signed-off-by: Stefan Roesch > --- > Documentation/admin-guide/mm/ksm.rst | 54 ++++++++++++++++++++++++++++ > 1 file changed, 54 insertions(+) > > diff --git a/Documentation/admin-guide/mm/ksm.rst b/Documentation/admin-guide/mm/ksm.rst > index e59231ac6bb71..297c4a0d04dee 100644 > --- a/Documentation/admin-guide/mm/ksm.rst > +++ b/Documentation/admin-guide/mm/ksm.rst > @@ -80,6 +80,9 @@ pages_to_scan > how many pages to scan before ksmd goes to sleep > e.g. ``echo 100 > /sys/kernel/mm/ksm/pages_to_scan``. > > + The pages_to_scan value cannot be changed if ``advisor_mode`` has > + been set to scan-time. > + > Default: 100 (chosen for demonstration purposes) > > sleep_millisecs > @@ -164,6 +167,29 @@ smart_scan > optimization is enabled. The ``pages_skipped`` metric shows how > effective the setting is. > > +advisor_mode > + The ``advisor_mode`` selects the current advisor. Two modes are > + supported: none and scan-time. The default is none. By setting > + ``advisor_mode`` to scan-time, the scan time advisor is enabled. > + The section about ``advisor`` explains in detail how the scan time > + advisor works. > + > +adivsor_max_cpu > + specifies the upper limit of the cpu percent usage of the ksmd > + background thread. The default is 70. > + > +advisor_target_scan_time > + specifies the target scan time in seconds to scan all the candidate > + pages. The default value is 200 seconds. > + > +advisor_min_pages > + specifies the lower limit of the ``pages_to_scan`` parameter of the > + scan time advisor. The default is 500. > + > +adivsor_max_pages > + specifies the upper limit of the ``pages_to_scan`` parameter of the > + scan time advisor. The default is 30000. > + > The effectiveness of KSM and MADV_MERGEABLE is shown in ``/sys/kernel/mm/ksm/``: > > general_profit > @@ -263,6 +289,34 @@ ksm_swpin_copy > note that KSM page might be copied when swapping in because do_swap_page() > cannot do all the locking needed to reconstitute a cross-anon_vma KSM page. > > +Advisor > +======= > + > +The number of candidate pages for KSM is dynamic. It can be often observed > +that during the startup of an application more candidate pages need to be > +processed. Without an advisor the ``pages_to_scan`` parameter needs to be > +sized for the maximum number of candidate pages. The scan time advisor can > +changes the ``pages_to_scan`` parameter based on demand. > + > +The advisor can be enabled, so KSM can automatically adapt to changes in the > +number of candidate pages to scan. Two advisors are implemented: none and > +scan-time. With none, no advisor is enabled. The default is none. > + > +The scan time advisor changes the ``pages_to_scan`` parameter based on the > +observed scan times. The possible values for the ``pages_to_scan`` parameter is > +limited by the ``advisor_max_cpu`` parameter. In addition there is also the > +``advisor_target_scan_time`` parameter. This parameter sets the target time to > +scan all the KSM candidate pages. The parameter ``advisor_target_scan_time`` > +decides how aggressive the scan time advisor scans candidate pages. Lower > +values make the scan time advisor to scan more aggresively. This is the most > +important parameter for the configuration of the scan time advisor. > + > +The initial value and the maximum value can be changed with ``advisor_min_pages`` > +and ``advisor_max_pages``. The default values are sufficient for most workloads. > + > +The ``pages_to_scan`` parameter is re-calculated after a scan has been completed. Acked-by: David Hildenbrand -- Cheers, David / dhildenb