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 390E4D711D1 for ; Wed, 20 Nov 2024 18:29:29 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C5F926B009C; Wed, 20 Nov 2024 13:29:28 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id C0EE86B00A0; Wed, 20 Nov 2024 13:29:28 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A884B6B00A1; Wed, 20 Nov 2024 13:29:28 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 8E5B36B009C for ; Wed, 20 Nov 2024 13:29:28 -0500 (EST) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 3D1EE1A0F0F for ; Wed, 20 Nov 2024 18:29:28 +0000 (UTC) X-FDA: 82807310712.14.D8B4F77 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf21.hostedemail.com (Postfix) with ESMTP id A01971C0009 for ; Wed, 20 Nov 2024 18:27:47 +0000 (UTC) Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=NXI+XTw4; spf=pass (imf21.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1732127120; 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=xCs7iTIJNkzy1KhjvLmAaqevnqcTQGBiRk9bohfxGPs=; b=HY/Iu+K7rvAoyA460N3YWSgPlbX2xttF7RBLirGmX1f0+ETGhrMsDHskL2HfB1oA027wJQ 62raZ5+c0q52gJ8Gy+QWpTPj+4r9IPhsiY7qsS/Co9DBsXr/8Ad/+M31deEkJBzPpbDtEu UZ0KyFU1l8Qa9YRL++LdbiWZ7m6TPas= ARC-Authentication-Results: i=1; imf21.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=NXI+XTw4; spf=pass (imf21.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1732127120; a=rsa-sha256; cv=none; b=cataaQqnbfzpNMIGs8n6cvLfg0Z9Nk4gjvB4509/ULD/4Ji77KjvQwj8b+ttaWazKc3U0o BDz9WdR0oNpgvcbsIW38IxZgpZZlwADxYPpjeainhKWDOrnrUar9H/b2y8QrluR754+sbe tzqc98SlV0xJLbMPGl2T5ZHiZwsUa4c= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1732127365; 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=xCs7iTIJNkzy1KhjvLmAaqevnqcTQGBiRk9bohfxGPs=; b=NXI+XTw4yL6Ly1Tqf5ZmNI7OGhG8qwK8uHeLeEAPInwSe2KjMvfVg9AbpSMZjeRJV8GyYy BcJKhmmmYGkhxbD3hhXDeo5el71vtaU8DboYVJkhzMOHsDSv33dktsg6OlxdlOJGS+bER+ PrOPjHCMCbnG/vtksnfNh6Ytecr9NE8= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-529-pvDB3x5PM7OAqK7xjlO2cg-1; Wed, 20 Nov 2024 13:29:22 -0500 X-MC-Unique: pvDB3x5PM7OAqK7xjlO2cg-1 X-Mimecast-MFC-AGG-ID: pvDB3x5PM7OAqK7xjlO2cg Received: by mail-wm1-f71.google.com with SMTP id 5b1f17b1804b1-4316ac69e6dso12035e9.0 for ; Wed, 20 Nov 2024 10:29:21 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1732127361; x=1732732161; h=content-transfer-encoding:in-reply-to:organization:autocrypt :content-language:from:references:cc:to:subject:user-agent :mime-version:date:message-id:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=xCs7iTIJNkzy1KhjvLmAaqevnqcTQGBiRk9bohfxGPs=; b=Cduy+PQkSu7ZEZzJzp4ix90LEQDOgwNWPr/o0BJt35UcmHZGdK4xLJAzfB7vgcBJbK MphKTRs57vhcpZXrSgcMHqHvExXiBTPpF3KiHgy790bVfE2h66Fwv0DoN7NVjBR5MyHM 2j0ODGOkFwCSX3n5kTwa4sQ1yua1l0X7Nd9noj1MvKjJq9WQoQt10gMzJ8r+gpxvkbk/ V3TwWFez/T2OrGTqTCD2iJ465LkwnVcgd3MZmYntLsyG/BquWCYiVhOL07YY6Af1EdoZ UP90qI2QQGEfCWNKyUcZVrN8udPXh9mAQh1hBCXCifhed+itH013LOKVYemBWY7AK+9h VzWw== X-Forwarded-Encrypted: i=1; AJvYcCVu0H3hr3eDQwAYeRzNYNUKwEQzLJNlFug7PlU9/2tObtVeSammeALHISb6p8wtEOoF8nOHuJ0WpQ==@kvack.org X-Gm-Message-State: AOJu0YzSiuukO96Q2fdKkrv9t1ck52/v+evK7FlM+Gf3rDihYycCEhLv 76h1johWDAVnqPSNCAS2jtd4Et7Vpyoe7sG3ouJwM2jpfCwX9oKrgi551JkSj/dqZ3iVzCpFQOQ 4tTN9s6rFbr50XAk6KuFKsrNc06h8Jfl3AYGMaNDZcNajsoMb X-Gm-Gg: ASbGncs91ZDMZGeu9b2x24Mdl9WY+lyIYNPMEnjtTS076cfbY8Csj3S2BUH6sbmVOJ8 hTVX5K4FlCwveMKDr3FEws/XsgYir765/h6moqlfxS0eWDFm7jTafGvVGqt7mkbw1trHW8JUvsf Wze0JOK1PGGTXZ9vP74W1UEHppyT8fPfA5P2j0cT9WmlyvCKtAVDiMuUIuXta1FWsH5Sj6esbcX BZ5B0jANNprD5fPA8CIpHFi7CgZxSEOLs+wCJ3i5QhdeS+pdPqTH5nSNAfxXiOmN4ki8s872l8Q ow6exa3Ir/V1DFFyCNY5bZZQfQT7cAV1ZPZf6nqie9+aDACjLD3kvkiWLcatMnLAniTbRMepFSA 7Tg== X-Received: by 2002:a05:600c:4504:b0:430:5654:45d0 with SMTP id 5b1f17b1804b1-433489b3dc4mr36321265e9.14.1732127360853; Wed, 20 Nov 2024 10:29:20 -0800 (PST) X-Google-Smtp-Source: AGHT+IEVhH45DncZkRLkGWEYic5HXC4ydjlOUpFmVslfUz0dJd4CdqCHxs+qDbL17KG8YydFigfirQ== X-Received: by 2002:a05:600c:4504:b0:430:5654:45d0 with SMTP id 5b1f17b1804b1-433489b3dc4mr36320935e9.14.1732127360476; Wed, 20 Nov 2024 10:29:20 -0800 (PST) Received: from ?IPV6:2003:cb:c705:4200:ce79:acf6:d832:60df? (p200300cbc7054200ce79acf6d83260df.dip0.t-ipconnect.de. [2003:cb:c705:4200:ce79:acf6:d832:60df]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-433b45fa706sm28765815e9.16.2024.11.20.10.29.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 20 Nov 2024 10:29:19 -0800 (PST) Message-ID: <74cbda4a-7820-45a9-a1b2-139da9dae593@redhat.com> Date: Wed, 20 Nov 2024 19:29:17 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 0/4] KVM: ioctl for populating guest_memfd To: kalyazin@amazon.com, pbonzini@redhat.com, corbet@lwn.net, kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Cc: jthoughton@google.com, brijesh.singh@amd.com, michael.roth@amd.com, graf@amazon.de, jgowans@amazon.com, roypat@amazon.co.uk, derekmn@amazon.com, nsaenz@amazon.es, xmarcalx@amazon.com, Sean Christopherson , linux-mm@kvack.org References: <20241024095429.54052-1-kalyazin@amazon.com> <08aeaf6e-dc89-413a-86a6-b9772c9b2faf@amazon.com> <01b0a528-bec0-41d7-80f6-8afe213bd56b@redhat.com> <55b6b3ec-eaa8-494b-9bc7-741fe0c3bc63@amazon.com> <9286da7a-9923-4a3b-a769-590e8824fa10@redhat.com> <03a12598-74aa-4202-a79a-668b45dbcc47@amazon.com> 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: <03a12598-74aa-4202-a79a-668b45dbcc47@amazon.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: DTUMoEWI3yrEQ-i6WRGNU2w3YdlrGBhaOWX3inp6Pt8_1732127361 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: A01971C0009 X-Stat-Signature: tasybi93b4fwcx7jc9r51i5btawr9air X-Rspam-User: X-HE-Tag: 1732127267-687446 X-HE-Meta: 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 GGCIfOpg ViFA89luURb4xUWIFp53YgmOp8UH2HacGdosWK5slYhvtbcEHDf78PELuDs0wALRRFIzJ98R7kRPTZP7vZF8aZPoNnEyPb/84O63sezAN3PhdSYiK2p6MFs7Pdetme/9ANv517zmLxZ5d2pgF2GUclSYHK/+7JqjKLpl3ufhhfeqtZlFlhNJh9m1u9hDXVJGeQKOzJaebfKUdjVpqLA4kl02JYGs855CjlGIRwySmPzv6QNeRnbISu6h/TZqjZkOX7gTiMBK+skMoa1jAG2lpxhng3TZS4kbt/li1phw0qHeYfFr9SxdfUuNPjArfYpn3XX8i1i3xKHuAQVDVVcHCWHGq86Y7GWUOcC7lP8HmyCzxkzCXmq0Msi6KnFOTbl/m7TqegXqG0jXU59jjDcm4ZVbrXyIPlGhdLoJGcpPsk4O6JGAxjuKrYb1fdEpIeJC+eWAL X-Bogosity: Ham, tests=bogofilter, spamicity=0.011423, 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 20.11.24 18:21, Nikita Kalyazin wrote: > > > On 20/11/2024 16:44, David Hildenbrand wrote: >>> If the problem is the "pagecache" overhead, then yes, it will be a >>> harder nut to crack. But maybe there are some low-hanging fruits to >>> optimize? Finding the main cause for the added overhead would be >>> interesting. > > Agreed, knowing the exact root cause would be really nice. > >> Can you compare uffdio_copy() when using anonymous memory vs. shmem? >> That's likely the best we could currently achieve with guest_memfd. > > Yeah, I was doing that too. It was about ~28% slower in my setup, while > with guest_memfd it was ~34% slower. I looked into uffdio_copy() for shmem and we still walk+modify page tables. In theory, we could try hacking that out: for filling the pagecache we would only need the vma properties, not the page table properties; that would then really resemble "only modify the pagecache". That would likely resemble what we would expect with guest_memfd: work only on the pagecache and not the page tables. So it's rather surprising that guest_memfd is slower than that, as it currently doesn't mess with user page tables at all. The variance of the data was quite > high so the difference may well be just noise. In other words, I'd be > much happier if we could bring guest_memfd (or even shmem) performance > closer to the anon/private than if we just equalised guest_memfd with > shmem (which are probably already pretty close). Makes sense. Best we can do is: anon: work only on page tables shmem/guest_memfd: work only on pageacache So at least "only one treelike structure to update". -- Cheers, David / dhildenb