From patchwork Fri Jan 3 21:17:04 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Duyck X-Patchwork-Id: 11317431 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 0078D1395 for ; Fri, 3 Jan 2020 21:17:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C8F26206DB for ; Fri, 3 Jan 2020 21:17:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="N80AAa3s" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728858AbgACVRI (ORCPT ); Fri, 3 Jan 2020 16:17:08 -0500 Received: from mail-pg1-f181.google.com ([209.85.215.181]:40603 "EHLO mail-pg1-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728848AbgACVRF (ORCPT ); Fri, 3 Jan 2020 16:17:05 -0500 Received: by mail-pg1-f181.google.com with SMTP id k25so23926060pgt.7; Fri, 03 Jan 2020 13:17:05 -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:in-reply-to:references :user-agent:mime-version:content-transfer-encoding; bh=yW1O0jjXB9z8bWi4RkuBpy5DqO+Vy5mEgFaRwUh2ELE=; b=N80AAa3s0zzd3IKELy/pbRakvvtwA55lPakZG0dcI6ezILUb1eCpIyR9Q1ehAbeKRD 2bbB4pS/D2iQTaP5M99p5+BeB3boYWFCkk0nwaydCdGDI16JTQJP7IWTqlTjRWmEqM8c L/Ze6ZVTH21A0XPI4MnVOIqXkIMzoxSxrWwuMLmApBmqIpafRJdLn2ybp5xAqNJJOO8V EjH2ROym8hZAoXkNPgXwY0zcbYZrL/ulVvHwud6NLmuOirehKNsZlr53orYwHCFyN1MY fI2C1dWH1Fp+ZJ2JmBkmVimkP1kWR5uBzOQ9rNc0tVAG55Y4WeMxBOThtX1j/ulvnnJj T6AQ== 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:in-reply-to :references:user-agent:mime-version:content-transfer-encoding; bh=yW1O0jjXB9z8bWi4RkuBpy5DqO+Vy5mEgFaRwUh2ELE=; b=J+1d2x7Bp+jhiSVDrSFxYpNJLFQedd65Ykhrd9imn0iVIqlpGrxF9HkMa6mc1LUyHL eSDtLEKfHjoAgXSbjYv6vJuq21ycT5z5+qC5wa+73OP1hhW300/7Yc1TQmfln1nzEPn5 atv74ypdlctXriFuSppAY8vUoH0z/yr4iNFWL0yTnRAd5CLX69KEtctNrREha/0Z0WtG mAfVxYK8BjpuSOolJCr4uDbyz3A23RTAkl9Y/Fazjm2aU8sICPgpoWG8c9sOZHHlxVo0 lpj7/yG6wtHfGlhjgkVTsOw62OGyfjCkcOQBA0z9atvKNoC8Ku4u3keR3rlaMd5Tj5JU ZqDg== X-Gm-Message-State: APjAAAWSU/h2ljidVVInHZzuATS7MZSIDgZnNJ3wBWz9fF8g+b4kYPXT 1v5L3b0dTKmbpjrGs2C3JTI= X-Google-Smtp-Source: APXvYqwsbem4TbYMQQreA2Pi/h0WlGAfaGKiQLSCp81sdU5fSB81pX1FGoqthPyYMX3DmCit7YbtBQ== X-Received: by 2002:aa7:9218:: with SMTP id 24mr95742121pfo.145.1578086224950; Fri, 03 Jan 2020 13:17:04 -0800 (PST) Received: from localhost.localdomain ([2001:470:b:9c3:9e5c:8eff:fe4f:f2d0]) by smtp.gmail.com with ESMTPSA id z16sm69364196pff.125.2020.01.03.13.17.04 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 03 Jan 2020 13:17:04 -0800 (PST) Subject: [PATCH v16 8/9] mm: Add budget limit to how many pages can be reported per list per pass 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: Fri, 03 Jan 2020 13:17:04 -0800 Message-ID: <20200103211703.29237.95865.stgit@localhost.localdomain> In-Reply-To: <20200103210509.29237.18426.stgit@localhost.localdomain> References: <20200103210509.29237.18426.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 From: Alexander Duyck In order to keep ourselves from reporting pages that are just going to be reused again in the case of heavy churn we can put a limit on how many total pages we will process per pass. Doing this will allow the worker thread to go into idle much more quickly so that we avoid competing with other threads that might be allocating or freeing pages. The logic added here will limit the worker thread to no more than one sixteenth of the total free pages in a given area per list. Once that limit is reached it will update the state so that at the end of the pass we will reschedule the worker to try again in 2 seconds when the memory churn has hopefully settled down. Again this optimization doesn't show much of a benefit in the standard case as the memory churn is minmal. However with page allocator shuffling enabled the gain is quite noticeable. Below are the results with a THP enabled version of the will-it-scale page_fault1 test showing the improvement in iterations for 16 processes or threads. Without: tasks processes processes_idle threads threads_idle 16 8283274.75 0.17 5594261.00 38.15 With: tasks processes processes_idle threads threads_idle 16 8767010.50 0.21 5791312.75 36.98 Signed-off-by: Alexander Duyck --- include/linux/page_reporting.h | 1 + mm/page_reporting.c | 33 ++++++++++++++++++++++++++++++++- 2 files changed, 33 insertions(+), 1 deletion(-) diff --git a/include/linux/page_reporting.h b/include/linux/page_reporting.h index 32355486f572..3b99e0ec24f2 100644 --- a/include/linux/page_reporting.h +++ b/include/linux/page_reporting.h @@ -5,6 +5,7 @@ #include #include +/* This value should always be a power of 2, see page_reporting_cycle() */ #define PAGE_REPORTING_CAPACITY 32 struct page_reporting_dev_info { diff --git a/mm/page_reporting.c b/mm/page_reporting.c index 6885e74c2367..3bbd471cfc81 100644 --- a/mm/page_reporting.c +++ b/mm/page_reporting.c @@ -114,6 +114,7 @@ void __page_reporting_notify(void) struct list_head *list = &area->free_list[mt]; unsigned int page_len = PAGE_SIZE << order; struct page *page, *next; + long budget; int err = 0; /* @@ -125,12 +126,39 @@ void __page_reporting_notify(void) spin_lock_irq(&zone->lock); + /* + * Limit how many calls we will be making to the page reporting + * device for this list. By doing this we avoid processing any + * given list for too long. + * + * The current value used allows us enough calls to process over a + * sixteenth of the current list plus one additional call to handle + * any pages that may have already been present from the previous + * list processed. This should result in us reporting all pages on + * an idle system in about 30 seconds. + * + * The division here should be cheap since PAGE_REPORTING_CAPACITY + * should always be a power of 2. + */ + budget = DIV_ROUND_UP(area->nr_free, PAGE_REPORTING_CAPACITY * 16); + /* loop through free list adding unreported pages to sg list */ list_for_each_entry_safe(page, next, list, lru) { /* We are going to skip over the reported pages. */ if (PageReported(page)) continue; + /* + * If we fully consumed our budget then update our + * state to indicate that we are requesting additional + * processing and exit this list. + */ + if (budget < 0) { + atomic_set(&prdev->state, PAGE_REPORTING_REQUESTED); + next = page; + break; + } + /* Attempt to pull page from list and place in scatterlist */ if (*offset) { if (!__isolate_free_page(page, order)) { @@ -146,7 +174,7 @@ void __page_reporting_notify(void) } /* - * Make the first non-processed page in the free list + * Make the first non-reported page in the free list * the new head of the free list before we release the * zone lock. */ @@ -162,6 +190,9 @@ void __page_reporting_notify(void) /* reset offset since the full list was reported */ *offset = PAGE_REPORTING_CAPACITY; + /* update budget to reflect call to report function */ + budget--; + /* reacquire zone lock and resume processing */ spin_lock_irq(&zone->lock);