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 X-Spam-Level: X-Spam-Status: No, score=-7.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D8B88C433E0 for ; Wed, 24 Feb 2021 15:57:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7BB8D64E6C for ; Wed, 24 Feb 2021 15:57:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236329AbhBXP43 (ORCPT ); Wed, 24 Feb 2021 10:56:29 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:39787 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233674AbhBXPIN (ORCPT ); Wed, 24 Feb 2021 10:08:13 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1614179169; 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; bh=hE/JW8Dw5e6ABCMHC+aiwNgbhT17E1ZqRTDBWqvHAHE=; b=cfyexALChXT7zf6RREJ6miqZmVm7cMzstEPTMK/60c0vQpYfudYhR/1wnmhOp1U8bOmvlw iMfhOLHmwQWwHCQmdt8KONIfQeSZDG+NCNYjOnt4rsadI0dpuWps7iNJt4Tsr7vUqoaQZi j3SyFP/HVH0FdusxSM6519z7aILY9HY= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-237-WeJ4SY0uNIOI_e9AL1yUkw-1; Wed, 24 Feb 2021 10:06:05 -0500 X-MC-Unique: WeJ4SY0uNIOI_e9AL1yUkw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A17918C6C52; Wed, 24 Feb 2021 14:38:34 +0000 (UTC) Received: from [10.36.114.83] (ovpn-114-83.ams2.redhat.com [10.36.114.83]) by smtp.corp.redhat.com (Postfix) with ESMTP id B293D19D9C; Wed, 24 Feb 2021 14:38:25 +0000 (UTC) Subject: Re: [PATCH RFC] mm/madvise: introduce MADV_POPULATE to prefault/prealloc memory From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Andrew Morton , Arnd Bergmann , Michal Hocko , Oscar Salvador , Matthew Wilcox , Andrea Arcangeli , Minchan Kim , Jann Horn , Jason Gunthorpe , Dave Hansen , Hugh Dickins , Rik van Riel , "Michael S . Tsirkin" , "Kirill A . Shutemov" , Vlastimil Babka , Richard Henderson , Ivan Kokshaysky , Matt Turner , Thomas Bogendoerfer , "James E.J. Bottomley" , Helge Deller , Chris Zankel , Max Filippov , linux-alpha@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-xtensa@linux-xtensa.org, linux-arch@vger.kernel.org References: <20210217154844.12392-1-david@redhat.com> <4bb9071b-e6c1-a732-0ed6-46aff0eaa70c@redhat.com> Organization: Red Hat GmbH Message-ID: <0f1c6f39-6a51-f8a6-8542-be1eb9c6fa0a@redhat.com> Date: Wed, 24 Feb 2021 15:38:24 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: <4bb9071b-e6c1-a732-0ed6-46aff0eaa70c@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org On 24.02.21 15:25, David Hildenbrand wrote: >> + tmp_end = min_t(unsigned long, end, vma->vm_end); >> + pages = populate_vma_page_range(vma, start, tmp_end, &locked); >> + if (!locked) { >> + mmap_read_lock(mm); >> + *prev = NULL; >> + vma = NULL; > > ^ locked = 1; is missing here. > > > --- Simple benchmark --- > > I implemented MADV_POPULATE_READ and MADV_POPULATE_WRITE and performed > some simple measurements to simulate memory preallocation with empty files: > > 1) mmap a 2 MiB/128 MiB/4 GiB region (anonymous, memfd, memfd hugetlb) > 2) Discard all memory using fallocate/madvise > 3) Prefault memory using different approaches and measure the time this > takes. > > I repeat 2)+3) 10 times and compute the average. I only use a single thread. > > Read: Read from each page a byte. > Write: Write one byte of each page (0). > Read/Write: Read one byte and write the value back for each page > POPULATE: MADV_POPULATE (this patch) > POPULATE_READ: MADV_POPULATE_READ > POPULATE_WRITE: MADV_POPULATE_WRITE > > --- Benchmark results --- > > Measuring 10 iterations each: > ================================================== > 2 MiB MAP_PRIVATE: > ************************************************** > Anonymous : Read : 0.159 ms > Anonymous : Write : 0.244 ms > Anonymous : Read+Write : 0.383 ms > Anonymous : POPULATE : 0.167 ms > Anonymous : POPULATE_READ : 0.064 ms > Anonymous : POPULATE_WRITE : 0.165 ms > Memfd 4 KiB : Read : 0.401 ms > Memfd 4 KiB : Write : 0.056 ms > Memfd 4 KiB : Read+Write : 0.075 ms > Memfd 4 KiB : POPULATE : 0.057 ms > Memfd 4 KiB : POPULATE_READ : 0.337 ms > Memfd 4 KiB : POPULATE_WRITE : 0.056 ms > Memfd 2 MiB : Read : 0.041 ms > Memfd 2 MiB : Write : 0.030 ms > Memfd 2 MiB : Read+Write : 0.031 ms > Memfd 2 MiB : POPULATE : 0.031 ms > Memfd 2 MiB : POPULATE_READ : 0.031 ms > Memfd 2 MiB : POPULATE_WRITE : 0.031 ms > ************************************************** > 2 MiB MAP_SHARED: > ************************************************** > Anonymous : Read : 0.071 ms > Anonymous : Write : 0.181 ms > Anonymous : Read+Write : 0.081 ms > Anonymous : POPULATE : 0.069 ms > Anonymous : POPULATE_READ : 0.069 ms > Anonymous : POPULATE_WRITE : 0.115 ms > Memfd 4 KiB : Read : 0.401 ms > Memfd 4 KiB : Write : 0.351 ms > Memfd 4 KiB : Read+Write : 0.414 ms > Memfd 4 KiB : POPULATE : 0.338 ms > Memfd 4 KiB : POPULATE_READ : 0.339 ms > Memfd 4 KiB : POPULATE_WRITE : 0.279 ms > Memfd 2 MiB : Read : 0.031 ms > Memfd 2 MiB : Write : 0.031 ms > Memfd 2 MiB : Read+Write : 0.031 ms > Memfd 2 MiB : POPULATE : 0.031 ms > Memfd 2 MiB : POPULATE_READ : 0.031 ms > Memfd 2 MiB : POPULATE_WRITE : 0.031 ms > ************************************************** > 128 MiB MAP_PRIVATE: > ************************************************** > Anonymous : Read : 7.517 ms > Anonymous : Write : 22.503 ms > Anonymous : Read+Write : 33.186 ms > Anonymous : POPULATE : 18.381 ms > Anonymous : POPULATE_READ : 3.952 ms > Anonymous : POPULATE_WRITE : 18.354 ms > Memfd 4 KiB : Read : 34.300 ms > Memfd 4 KiB : Write : 4.659 ms > Memfd 4 KiB : Read+Write : 6.531 ms > Memfd 4 KiB : POPULATE : 5.219 ms > Memfd 4 KiB : POPULATE_READ : 29.744 ms > Memfd 4 KiB : POPULATE_WRITE : 5.244 ms > Memfd 2 MiB : Read : 10.228 ms > Memfd 2 MiB : Write : 10.130 ms > Memfd 2 MiB : Read+Write : 10.190 ms > Memfd 2 MiB : POPULATE : 10.007 ms > Memfd 2 MiB : POPULATE_READ : 10.008 ms > Memfd 2 MiB : POPULATE_WRITE : 10.010 ms > ************************************************** > 128 MiB MAP_SHARED: > ************************************************** > Anonymous : Read : 7.295 ms > Anonymous : Write : 15.234 ms > Anonymous : Read+Write : 7.460 ms > Anonymous : POPULATE : 5.196 ms > Anonymous : POPULATE_READ : 5.190 ms > Anonymous : POPULATE_WRITE : 8.245 ms > Memfd 4 KiB : Read : 34.412 ms > Memfd 4 KiB : Write : 30.586 ms > Memfd 4 KiB : Read+Write : 35.157 ms > Memfd 4 KiB : POPULATE : 29.643 ms > Memfd 4 KiB : POPULATE_READ : 29.691 ms > Memfd 4 KiB : POPULATE_WRITE : 25.790 ms > Memfd 2 MiB : Read : 10.210 ms > Memfd 2 MiB : Write : 10.074 ms > Memfd 2 MiB : Read+Write : 10.068 ms > Memfd 2 MiB : POPULATE : 10.034 ms > Memfd 2 MiB : POPULATE_READ : 10.037 ms > Memfd 2 MiB : POPULATE_WRITE : 10.031 ms > ************************************************** > 4096 MiB MAP_PRIVATE: > ************************************************** > Anonymous : Read : 240.947 ms > Anonymous : Write : 712.941 ms > Anonymous : Read+Write : 1027.636 ms > Anonymous : POPULATE : 571.816 ms > Anonymous : POPULATE_READ : 120.215 ms > Anonymous : POPULATE_WRITE : 570.750 ms > Memfd 4 KiB : Read : 1054.739 ms > Memfd 4 KiB : Write : 145.534 ms > Memfd 4 KiB : Read+Write : 202.275 ms > Memfd 4 KiB : POPULATE : 162.597 ms > Memfd 4 KiB : POPULATE_READ : 914.747 ms > Memfd 4 KiB : POPULATE_WRITE : 161.281 ms > Memfd 2 MiB : Read : 351.818 ms > Memfd 2 MiB : Write : 352.357 ms > Memfd 2 MiB : Read+Write : 352.762 ms > Memfd 2 MiB : POPULATE : 351.471 ms > Memfd 2 MiB : POPULATE_READ : 351.553 ms > Memfd 2 MiB : POPULATE_WRITE : 351.931 ms > ************************************************** > 4096 MiB MAP_SHARED: > ************************************************** > Anonymous : Read : 229.338 ms > Anonymous : Write : 478.964 ms > Anonymous : Read+Write : 234.546 ms > Anonymous : POPULATE : 161.635 ms > Anonymous : POPULATE_READ : 160.943 ms > Anonymous : POPULATE_WRITE : 252.686 ms > Memfd 4 KiB : Read : 1052.828 ms > Memfd 4 KiB : Write : 929.237 ms > Memfd 4 KiB : Read+Write : 1074.494 ms > Memfd 4 KiB : POPULATE : 915.663 ms > Memfd 4 KiB : POPULATE_READ : 915.001 ms > Memfd 4 KiB : POPULATE_WRITE : 787.388 ms > Memfd 2 MiB : Read : 353.580 ms > Memfd 2 MiB : Write : 353.197 ms > Memfd 2 MiB : Read+Write : 353.172 ms > Memfd 2 MiB : POPULATE : 353.686 ms > Memfd 2 MiB : POPULATE_READ : 353.465 ms > Memfd 2 MiB : POPULATE_WRITE : 352.776 ms > ************************************************** > > > --- Discussion --- > > 1) With huge pages, the performance benefit is negligible with the sizes > I tried, because there are little actual page faults. Most time is spent > zeroing huge pages I guess. It will take quite a lot of memory to pay off. > > 2) In all 4k cases, the POPULATE_READ/POPULATE_WRITE variants are faster > than manually reading or writing from user space. Forgot to mention one case: Except on Memfd 4 KiB with MAP_PRIVATE: POPULATE_WRITE is slower than a simple write. And a read fault is exceptionally slower than a write fault (what?). -- Thanks, David / dhildenb From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hildenbrand Subject: Re: [PATCH RFC] mm/madvise: introduce MADV_POPULATE to prefault/prealloc memory Date: Wed, 24 Feb 2021 15:38:24 +0100 Message-ID: <0f1c6f39-6a51-f8a6-8542-be1eb9c6fa0a@redhat.com> References: <20210217154844.12392-1-david@redhat.com> <4bb9071b-e6c1-a732-0ed6-46aff0eaa70c@redhat.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1614179169; 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; bh=hE/JW8Dw5e6ABCMHC+aiwNgbhT17E1ZqRTDBWqvHAHE=; b=cfyexALChXT7zf6RREJ6miqZmVm7cMzstEPTMK/60c0vQpYfudYhR/1wnmhOp1U8bOmvlw iMfhOLHmwQWwHCQmdt8KONIfQeSZDG+NCNYjOnt4rsadI0dpuWps7iNJt4Tsr7vUqoaQZi j3SyFP/HVH0FdusxSM6519z7aILY9HY= In-Reply-To: <4bb9071b-e6c1-a732-0ed6-46aff0eaa70c@redhat.com> Content-Language: en-US List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Andrew Morton , Arnd Bergmann , Michal Hocko , Oscar Salvador , Matthew Wilcox , Andrea Arcangeli , Minchan Kim , Jann Horn , Jason Gunthorpe , Dave Hansen , Hugh Dickins , Rik van Riel , "Michael S . Tsirkin" , "Kirill A . Shutemov" , Vlastimil Babka , Richard Henderson , Ivan Kokshaysky , Matt Turner , Thomas Bogendoerfer , "James E.J. Bottomley" On 24.02.21 15:25, David Hildenbrand wrote: >> + tmp_end = min_t(unsigned long, end, vma->vm_end); >> + pages = populate_vma_page_range(vma, start, tmp_end, &locked); >> + if (!locked) { >> + mmap_read_lock(mm); >> + *prev = NULL; >> + vma = NULL; > > ^ locked = 1; is missing here. > > > --- Simple benchmark --- > > I implemented MADV_POPULATE_READ and MADV_POPULATE_WRITE and performed > some simple measurements to simulate memory preallocation with empty files: > > 1) mmap a 2 MiB/128 MiB/4 GiB region (anonymous, memfd, memfd hugetlb) > 2) Discard all memory using fallocate/madvise > 3) Prefault memory using different approaches and measure the time this > takes. > > I repeat 2)+3) 10 times and compute the average. I only use a single thread. > > Read: Read from each page a byte. > Write: Write one byte of each page (0). > Read/Write: Read one byte and write the value back for each page > POPULATE: MADV_POPULATE (this patch) > POPULATE_READ: MADV_POPULATE_READ > POPULATE_WRITE: MADV_POPULATE_WRITE > > --- Benchmark results --- > > Measuring 10 iterations each: > ================================================== > 2 MiB MAP_PRIVATE: > ************************************************** > Anonymous : Read : 0.159 ms > Anonymous : Write : 0.244 ms > Anonymous : Read+Write : 0.383 ms > Anonymous : POPULATE : 0.167 ms > Anonymous : POPULATE_READ : 0.064 ms > Anonymous : POPULATE_WRITE : 0.165 ms > Memfd 4 KiB : Read : 0.401 ms > Memfd 4 KiB : Write : 0.056 ms > Memfd 4 KiB : Read+Write : 0.075 ms > Memfd 4 KiB : POPULATE : 0.057 ms > Memfd 4 KiB : POPULATE_READ : 0.337 ms > Memfd 4 KiB : POPULATE_WRITE : 0.056 ms > Memfd 2 MiB : Read : 0.041 ms > Memfd 2 MiB : Write : 0.030 ms > Memfd 2 MiB : Read+Write : 0.031 ms > Memfd 2 MiB : POPULATE : 0.031 ms > Memfd 2 MiB : POPULATE_READ : 0.031 ms > Memfd 2 MiB : POPULATE_WRITE : 0.031 ms > ************************************************** > 2 MiB MAP_SHARED: > ************************************************** > Anonymous : Read : 0.071 ms > Anonymous : Write : 0.181 ms > Anonymous : Read+Write : 0.081 ms > Anonymous : POPULATE : 0.069 ms > Anonymous : POPULATE_READ : 0.069 ms > Anonymous : POPULATE_WRITE : 0.115 ms > Memfd 4 KiB : Read : 0.401 ms > Memfd 4 KiB : Write : 0.351 ms > Memfd 4 KiB : Read+Write : 0.414 ms > Memfd 4 KiB : POPULATE : 0.338 ms > Memfd 4 KiB : POPULATE_READ : 0.339 ms > Memfd 4 KiB : POPULATE_WRITE : 0.279 ms > Memfd 2 MiB : Read : 0.031 ms > Memfd 2 MiB : Write : 0.031 ms > Memfd 2 MiB : Read+Write : 0.031 ms > Memfd 2 MiB : POPULATE : 0.031 ms > Memfd 2 MiB : POPULATE_READ : 0.031 ms > Memfd 2 MiB : POPULATE_WRITE : 0.031 ms > ************************************************** > 128 MiB MAP_PRIVATE: > ************************************************** > Anonymous : Read : 7.517 ms > Anonymous : Write : 22.503 ms > Anonymous : Read+Write : 33.186 ms > Anonymous : POPULATE : 18.381 ms > Anonymous : POPULATE_READ : 3.952 ms > Anonymous : POPULATE_WRITE : 18.354 ms > Memfd 4 KiB : Read : 34.300 ms > Memfd 4 KiB : Write : 4.659 ms > Memfd 4 KiB : Read+Write : 6.531 ms > Memfd 4 KiB : POPULATE : 5.219 ms > Memfd 4 KiB : POPULATE_READ : 29.744 ms > Memfd 4 KiB : POPULATE_WRITE : 5.244 ms > Memfd 2 MiB : Read : 10.228 ms > Memfd 2 MiB : Write : 10.130 ms > Memfd 2 MiB : Read+Write : 10.190 ms > Memfd 2 MiB : POPULATE : 10.007 ms > Memfd 2 MiB : POPULATE_READ : 10.008 ms > Memfd 2 MiB : POPULATE_WRITE : 10.010 ms > ************************************************** > 128 MiB MAP_SHARED: > ************************************************** > Anonymous : Read : 7.295 ms > Anonymous : Write : 15.234 ms > Anonymous : Read+Write : 7.460 ms > Anonymous : POPULATE : 5.196 ms > Anonymous : POPULATE_READ : 5.190 ms > Anonymous : POPULATE_WRITE : 8.245 ms > Memfd 4 KiB : Read : 34.412 ms > Memfd 4 KiB : Write : 30.586 ms > Memfd 4 KiB : Read+Write : 35.157 ms > Memfd 4 KiB : POPULATE : 29.643 ms > Memfd 4 KiB : POPULATE_READ : 29.691 ms > Memfd 4 KiB : POPULATE_WRITE : 25.790 ms > Memfd 2 MiB : Read : 10.210 ms > Memfd 2 MiB : Write : 10.074 ms > Memfd 2 MiB : Read+Write : 10.068 ms > Memfd 2 MiB : POPULATE : 10.034 ms > Memfd 2 MiB : POPULATE_READ : 10.037 ms > Memfd 2 MiB : POPULATE_WRITE : 10.031 ms > ************************************************** > 4096 MiB MAP_PRIVATE: > ************************************************** > Anonymous : Read : 240.947 ms > Anonymous : Write : 712.941 ms > Anonymous : Read+Write : 1027.636 ms > Anonymous : POPULATE : 571.816 ms > Anonymous : POPULATE_READ : 120.215 ms > Anonymous : POPULATE_WRITE : 570.750 ms > Memfd 4 KiB : Read : 1054.739 ms > Memfd 4 KiB : Write : 145.534 ms > Memfd 4 KiB : Read+Write : 202.275 ms > Memfd 4 KiB : POPULATE : 162.597 ms > Memfd 4 KiB : POPULATE_READ : 914.747 ms > Memfd 4 KiB : POPULATE_WRITE : 161.281 ms > Memfd 2 MiB : Read : 351.818 ms > Memfd 2 MiB : Write : 352.357 ms > Memfd 2 MiB : Read+Write : 352.762 ms > Memfd 2 MiB : POPULATE : 351.471 ms > Memfd 2 MiB : POPULATE_READ : 351.553 ms > Memfd 2 MiB : POPULATE_WRITE : 351.931 ms > ************************************************** > 4096 MiB MAP_SHARED: > ************************************************** > Anonymous : Read : 229.338 ms > Anonymous : Write : 478.964 ms > Anonymous : Read+Write : 234.546 ms > Anonymous : POPULATE : 161.635 ms > Anonymous : POPULATE_READ : 160.943 ms > Anonymous : POPULATE_WRITE : 252.686 ms > Memfd 4 KiB : Read : 1052.828 ms > Memfd 4 KiB : Write : 929.237 ms > Memfd 4 KiB : Read+Write : 1074.494 ms > Memfd 4 KiB : POPULATE : 915.663 ms > Memfd 4 KiB : POPULATE_READ : 915.001 ms > Memfd 4 KiB : POPULATE_WRITE : 787.388 ms > Memfd 2 MiB : Read : 353.580 ms > Memfd 2 MiB : Write : 353.197 ms > Memfd 2 MiB : Read+Write : 353.172 ms > Memfd 2 MiB : POPULATE : 353.686 ms > Memfd 2 MiB : POPULATE_READ : 353.465 ms > Memfd 2 MiB : POPULATE_WRITE : 352.776 ms > ************************************************** > > > --- Discussion --- > > 1) With huge pages, the performance benefit is negligible with the sizes > I tried, because there are little actual page faults. Most time is spent > zeroing huge pages I guess. It will take quite a lot of memory to pay off. > > 2) In all 4k cases, the POPULATE_READ/POPULATE_WRITE variants are faster > than manually reading or writing from user space. Forgot to mention one case: Except on Memfd 4 KiB with MAP_PRIVATE: POPULATE_WRITE is slower than a simple write. And a read fault is exceptionally slower than a write fault (what?). -- Thanks, David / dhildenb