From patchwork Thu Dec 5 16:22:04 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Duyck X-Patchwork-Id: 11275147 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8A36C13A4 for ; Thu, 5 Dec 2019 16:22:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5498D24249 for ; Thu, 5 Dec 2019 16:22:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ntv2TvpP" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729712AbfLEQWJ (ORCPT ); Thu, 5 Dec 2019 11:22:09 -0500 Received: from mail-qv1-f66.google.com ([209.85.219.66]:36845 "EHLO mail-qv1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726589AbfLEQWJ (ORCPT ); Thu, 5 Dec 2019 11:22:09 -0500 Received: by mail-qv1-f66.google.com with SMTP id b18so1501350qvy.3; Thu, 05 Dec 2019 08:22:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:from:to:cc:date:message-id:user-agent:mime-version :content-transfer-encoding; bh=Qpy6K11ax0kK4ciQM3JG1UmIIJR6lqYusM7Lr8kdIP8=; b=ntv2TvpPrlFC29Z8dt/yFPk4ZU994TTQ3MZxhlyx8CDhllpFCkt1k0VdcVvV+LkFMp uUDkD8rqa0Y4bdl+vaVC/fhOAZnX4K59HT0mkWWTQpL3bdIXlMc61SQvb54rSPyS2cKO cPxqyLngQTmFZ8SiaUMtZAz8cXN4ASiptX4Iy4eDhQf1OmA71uIeM9Hx53CJ7NAekVun HrldzA1OcjEJM6gE7yPe95LhBut6gzyqVDpOJ2UHhzlCKTejOXmo37zcwwzaA1nT4Lgd r5TtlMdPut6l1Dwoa6rgTq6t2IdVs4EKTPu/Ca+KbazPcNt1cvAfyJclBoT1i4m92aVz 1/OQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:from:to:cc:date:message-id:user-agent :mime-version:content-transfer-encoding; bh=Qpy6K11ax0kK4ciQM3JG1UmIIJR6lqYusM7Lr8kdIP8=; b=KcIM2gNc1p77l3nvxJekNIyCKTomQXyc+l8LUN2wJMILwD+TxZpLFH8BXd4562yMGD PnBMcw1kEZrgq5xcUyKZD4L/9fp3nwGTvgiOqWDLx+0L5nSHoVpyBZuDkUZBLgD9Yjle Yo06+VSLJx3sQdAeL+/Ei6QL9J1Xk39WrwbTbOGOj1rmB2G0LrT/v2Ht9pew2DNo9ioB 8Bxp+iax+kajf1vhCwjqqJ1wmgg8DYi+k1m4p46glzwU0Dbe1zM1680bmQkDAdwRJyn3 v/WgFsudBJ7Ah0/Brh+N84w9uTEhDxgUzjmHXiq0e+RtB+V5vVvUgYGZIbttETPoVrJ1 syWA== X-Gm-Message-State: APjAAAULIAFBTjOLfqTTdhWxVUpV0GqeFx0OmfhRXF7SAD3lepsjj4Ac OP8nYaOaQeGg3e711MDc2+o= X-Google-Smtp-Source: APXvYqywFjguj3KYPD3Q9UUX11DryNlxCYob26zjWKeo8xEpYWA1gNBELiUDvYTJzAtTA+o2WPVuRg== X-Received: by 2002:a05:6214:844:: with SMTP id dg4mr8101649qvb.94.1575562927636; Thu, 05 Dec 2019 08:22:07 -0800 (PST) Received: from localhost.localdomain ([2001:470:b:9c3:9e5c:8eff:fe4f:f2d0]) by smtp.gmail.com with ESMTPSA id 17sm5511558qtz.85.2019.12.05.08.22.04 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 05 Dec 2019 08:22:06 -0800 (PST) Subject: [PATCH v15 0/7] mm / virtio: Provide support for free page reporting From: Alexander Duyck To: kvm@vger.kernel.org, mst@redhat.com, linux-kernel@vger.kernel.org, willy@infradead.org, mhocko@kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, mgorman@techsingularity.net, vbabka@suse.cz Cc: yang.zhang.wz@gmail.com, nitesh@redhat.com, konrad.wilk@oracle.com, david@redhat.com, pagupta@redhat.com, riel@surriel.com, lcapitulino@redhat.com, dave.hansen@intel.com, wei.w.wang@intel.com, aarcange@redhat.com, pbonzini@redhat.com, dan.j.williams@intel.com, alexander.h.duyck@linux.intel.com, osalvador@suse.de Date: Thu, 05 Dec 2019 08:22:04 -0800 Message-ID: <20191205161928.19548.41654.stgit@localhost.localdomain> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org This series provides an asynchronous means of reporting free guest pages to a hypervisor so that the memory associated with those pages can be dropped and reused by other processes and/or guests on the host. Using this it is possible to avoid unnecessary I/O to disk and greatly improve performance in the case of memory overcommit on the host. When enabled we will be performing a scan of free memory every 2 seconds while pages of sufficiently high order are being freed. Currently the order used is pageblock_order so that this feature will not interfere with the use of Transparent Huge Pages in the case of virtualization. Currently this is only in use by virtio-balloon however there is the hope that at some point in the future other hypervisors might be able to make use of it. In the virtio-balloon/QEMU implementation the hypervisor is currently using MADV_DONTNEED to indicate to the host kernel that the page is currently free. It will be zeroed and faulted back into the guest the next time the page is accessed. To track if a page is reported or not the Uptodate flag was repurposed and used as a Reported flag for Buddy pages. We walk though the free list isolating pages and adding them to the scatterlist until we either encounter the end of the list, processed as many pages as were listed in nr_free prior to us starting, or have filled the scatterlist with pages to be reported. If we fill the scatterlist before we reach the end of the list we rotate the list so that the first unreported page we encounter is moved to the head of the list as that is where we will resume after we have freed the reported pages back into the tail of the list. Below are the results from various benchmarks. I primarily focused on two tests. The first is the will-it-scale/page_fault2 test, and the other is a modified version of will-it-scale/page_fault1 that was enabled to use THP. I did this as it allows for better visibility into different parts of the memory subsystem. The guest is running with 32G for RAM on one node of a E5-2630 v3. The host has had some power saving features disabled by setting the /dev/cpu_dma_latency value to 10ms. Test page_fault1 (THP) page_fault2 Name tasks Process Iter STDEV Process Iter STDEV Baseline 1 1208307.25 0.10% 408596.00 0.19% 16 8865204.75 0.16% 3344169.00 0.60% Patches applied 1 1206809.00 0.26% 412558.25 0.32% 16 8814350.50 0.78% 3420102.00 1.16% Patches enabled 1 1201386.25 0.21% 407903.75 0.32% 16 8880178.00 0.08% 3396700.50 0.54% Patches enabled 1 1173529.00 1.04% 409006.50 0.45% page shuffle 16 8384540.25 0.74% 3288289.25 0.41% Patches enabled 1 1193411.00 0.33% 406333.50 0.09% shuffle w/ RFC 16 8812639.75 0.73% 3321706.25 0.53% The results above are for a baseline with a linux-next-20191203 kernel, that kernel with this patch set applied but page reporting disabled in virtio-balloon, the patches applied and page reporting fully enabled, the patches enabled with page shuffling enabled, and the patches applied with page shuffling enabled and an RFC patch that makes used of MADV_FREE in QEMU. These results include the deviation seen between the average value reported here versus the high and/or low value. I observed that during the test memory usage for the first three tests never dropped whereas with the patches fully enabled the VM would drop to using only a few GB of the host's memory when switching from memhog to page fault tests. Any of the overhead visible with this patch set enabled seems due to page faults caused by accessing the reported pages and the host zeroing the page before giving it back to the guest. This overhead is much more visible when using THP than with standard 4K pages. In addition page shuffling seemed to increase the amount of faults generated due to an increase in memory churn. As seen in the data above, using MADV_FREE in QEMU mostly eliminates this overhead. The overall guest size is kept fairly small to only a few GB while the test is running. If the host memory were oversubscribed this patch set should result in a performance improvement as swapping memory in the host can be avoided. A brief history on the background of free page reporting can be found at: https://lore.kernel.org/lkml/29f43d5796feed0dec8e8bb98b187d9dac03b900.camel@linux.intel.com/ Changes from v13: https://lore.kernel.org/lkml/20191105215940.15144.65968.stgit@localhost.localdomain/ Rewrote core reporting functionality Merged patches 3 & 4 Dropped boundary list and related code Folded get_reported_page into page_reporting_fill Folded page_reporting_fill into page_reporting_cycle Pulled reporting functionality out of free_reported_page Renamed it to __free_isolated_page Moved page reporting specific bits to page_reporting_drain Renamed phdev to prdev since we aren't "hinting" we are "reporting" Added documentation to describe the usage of unused page reporting Updated cover page and patch descriptions to avoid mention of boundary Changes from v14: https://lore.kernel.org/lkml/20191119214454.24996.66289.stgit@localhost.localdomain/ Renamed "unused page reporting" to "free page reporting" Updated code, kconfig, and patch descriptions Split out patch for __free_isolated_page Renamed function to __putback_isolated_page Rewrote core reporting functionality Added logic to reschedule worker in 2 seconds instead of run to completion Removed reported_pages statistics Removed REPORTING_REQUESTED bit used in zone flags Replaced page_reporting_dev_info refcount with state variable Removed scatterlist from page_reporting_dev_info Removed capacity from page reporting device Added dynamic scatterlist allocation/free at start/end of reporting process Updated __free_one_page so that reported pages are not always added to tail Added logic to handle error from report function Updated virtio-balloon patch that adds support for page reporting Updated patch description to try and highlight differences in approaches Updated logic to reflect that we cannot limit the scatterlist from device Added logic to return error from report function Moved documentation patch to end of patch set --- Alexander Duyck (7): mm: Adjust shuffle code to allow for future coalescing mm: Use zone and order instead of free area in free_list manipulators mm: Add function __putback_isolated_page mm: Introduce Reported pages virtio-balloon: Pull page poisoning config out of free page hinting virtio-balloon: Add support for providing free page reports to host mm: Add free page reporting documentation Documentation/vm/free_page_reporting.rst | 41 ++++ drivers/virtio/Kconfig | 1 drivers/virtio/virtio_balloon.c | 87 +++++++- include/linux/mmzone.h | 44 ---- include/linux/page-flags.h | 11 + include/linux/page_reporting.h | 25 ++ include/uapi/linux/virtio_balloon.h | 1 mm/Kconfig | 11 + mm/Makefile | 1 mm/internal.h | 1 mm/page_alloc.c | 169 +++++++++++---- mm/page_isolation.c | 6 - mm/page_reporting.c | 336 ++++++++++++++++++++++++++++++ mm/page_reporting.h | 54 +++++ mm/shuffle.c | 12 + mm/shuffle.h | 6 + 16 files changed, 700 insertions(+), 106 deletions(-) create mode 100644 Documentation/vm/free_page_reporting.rst create mode 100644 include/linux/page_reporting.h create mode 100644 mm/page_reporting.c create mode 100644 mm/page_reporting.h --