From patchwork Wed Sep 4 15:10:30 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Duyck X-Patchwork-Id: 11130911 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 211DC17EF for ; Wed, 4 Sep 2019 15:10:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E3AA122CF7 for ; Wed, 4 Sep 2019 15:10:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="FIPxE9Sc" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731294AbfIDPKd (ORCPT ); Wed, 4 Sep 2019 11:10:33 -0400 Received: from mail-pf1-f195.google.com ([209.85.210.195]:34824 "EHLO mail-pf1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731197AbfIDPKc (ORCPT ); Wed, 4 Sep 2019 11:10:32 -0400 Received: by mail-pf1-f195.google.com with SMTP id 205so10982268pfw.2; Wed, 04 Sep 2019 08:10:32 -0700 (PDT) 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=HfMW8t+zdh/41N+suI9EkE4FGx0gR/oItAxCFwjZTI4=; b=FIPxE9Sc5P0KKx5FESIFqty+P+8FgJSSXdiHClQPAjNZ0IylFkpF3PL3gx4cTRHMBx Kmhr/yrySOO82rST2kSWcn4SUt0BHhBQ3Tnd0pdAeGk2wXelDgBRmHvHT/RcrkXqLYL7 vBuHpvFrUBR2c1hz8rdnX5W7GApOqPPnMZgAzPlyusQkg2SGIUDVdFyCcMzGhaSdJY4e 0dVv+u6K9+aX0lq3zyO2vZnaew4v96dHGlCyFeGq0Ao0uBEFOWsAU8FuSwkv2cGBOI6O f+mhMjeTz0s3+IfwZrTsbP/N8T92SSRcBjm0H6xFDubiGdUy3rRI5Vobxa8yEnGxteeV oYGA== 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=HfMW8t+zdh/41N+suI9EkE4FGx0gR/oItAxCFwjZTI4=; b=qx7pHZyxBep+MHGIUmtYZTthShiFzpb58ECqhuXBG5tx9ROeU49SzAYKZMoTsY9tfN VfbNITFJAFZo2G3HfKL/nYrCSA5uiDJQR3CUyeTpWawU3LIISaVMYwkXxzutfjGzJ6yk VUc1pNOnvfxg4JqZkR0VmmaJMZHXf8YpqOxkpI5MOJKMfLaikNL2AqvKo9S0pIXJFcOQ /W/3KGRsR/9NtpuGJO4IWxwW6h2iQQcdqTKf2XbpyikqMuztEB8T6stI+7moW+fxNlO6 39DQ9TQB4eZt3Iw31fweChSWIcnr/H3Cc4idtQjalgHTaEQsjU28SbhZOibJVe9TZPzp PmCw== X-Gm-Message-State: APjAAAWBLw39zkVi663j7UlExbkRiuF091Kq+kWCYl7Q9wxhuXAMbcc+ 0Ati1b7TWgaDXghwUrbxm+I= X-Google-Smtp-Source: APXvYqzfbf/ibco0qw0nwX2XuMugKIU3VWc4ZLn3x5GCY1E/khF+szbl2j8u5PpmmtjSz4dmwE7zfQ== X-Received: by 2002:a62:115:: with SMTP id 21mr21430403pfb.110.1567609831783; Wed, 04 Sep 2019 08:10:31 -0700 (PDT) Received: from localhost.localdomain ([2001:470:b:9c3:9e5c:8eff:fe4f:f2d0]) by smtp.gmail.com with ESMTPSA id x22sm5160594pfi.139.2019.09.04.08.10.30 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 04 Sep 2019 08:10:31 -0700 (PDT) Subject: [PATCH v7 1/6] mm: Adjust shuffle code to allow for future coalescing From: Alexander Duyck To: nitesh@redhat.com, kvm@vger.kernel.org, mst@redhat.com, david@redhat.com, dave.hansen@intel.com, linux-kernel@vger.kernel.org, willy@infradead.org, mhocko@kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, virtio-dev@lists.oasis-open.org, osalvador@suse.de Cc: yang.zhang.wz@gmail.com, pagupta@redhat.com, riel@surriel.com, konrad.wilk@oracle.com, lcapitulino@redhat.com, wei.w.wang@intel.com, aarcange@redhat.com, pbonzini@redhat.com, dan.j.williams@intel.com, alexander.h.duyck@linux.intel.com Date: Wed, 04 Sep 2019 08:10:30 -0700 Message-ID: <20190904151030.13848.25822.stgit@localhost.localdomain> In-Reply-To: <20190904150920.13848.32271.stgit@localhost.localdomain> References: <20190904150920.13848.32271.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 Move the head/tail adding logic out of the shuffle code and into the __free_one_page function since ultimately that is where it is really needed anyway. By doing this we should be able to reduce the overhead and can consolidate all of the list addition bits in one spot. While changing out the code I also opted to go for a bit more thread safe approach to getting the boolean value. This way we can avoid possible cache line bouncing of the batched entropy between CPUs. Signed-off-by: Alexander Duyck --- include/linux/mmzone.h | 12 -------- mm/page_alloc.c | 70 +++++++++++++++++++++++++++--------------------- mm/shuffle.c | 40 ++++++++++++++++----------- mm/shuffle.h | 12 ++++++++ 4 files changed, 75 insertions(+), 59 deletions(-) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index bda20282746b..125f300981c6 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -116,18 +116,6 @@ static inline void add_to_free_area_tail(struct page *page, struct free_area *ar area->nr_free++; } -#ifdef CONFIG_SHUFFLE_PAGE_ALLOCATOR -/* Used to preserve page allocation order entropy */ -void add_to_free_area_random(struct page *page, struct free_area *area, - int migratetype); -#else -static inline void add_to_free_area_random(struct page *page, - struct free_area *area, int migratetype) -{ - add_to_free_area(page, area, migratetype); -} -#endif - /* Used for pages which are on another list */ static inline void move_to_free_area(struct page *page, struct free_area *area, int migratetype) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index c5d62f1c2851..4e4356ba66c7 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -878,6 +878,36 @@ static inline struct capture_control *task_capc(struct zone *zone) #endif /* CONFIG_COMPACTION */ /* + * If this is not the largest possible page, check if the buddy + * of the next-highest order is free. If it is, it's possible + * that pages are being freed that will coalesce soon. In case, + * that is happening, add the free page to the tail of the list + * so it's less likely to be used soon and more likely to be merged + * as a higher order page + */ +static inline bool +buddy_merge_likely(unsigned long pfn, unsigned long buddy_pfn, + struct page *page, unsigned int order) +{ + struct page *higher_page, *higher_buddy; + unsigned long combined_pfn; + + if (order >= MAX_ORDER - 2) + return false; + + if (!pfn_valid_within(buddy_pfn)) + return false; + + combined_pfn = buddy_pfn & pfn; + higher_page = page + (combined_pfn - pfn); + buddy_pfn = __find_buddy_pfn(combined_pfn, order + 1); + higher_buddy = higher_page + (buddy_pfn - combined_pfn); + + return pfn_valid_within(buddy_pfn) && + page_is_buddy(higher_page, higher_buddy, order + 1); +} + +/* * Freeing function for a buddy system allocator. * * The concept of a buddy system is to maintain direct-mapped table @@ -906,11 +936,12 @@ static inline void __free_one_page(struct page *page, struct zone *zone, unsigned int order, int migratetype) { - unsigned long combined_pfn; + struct capture_control *capc = task_capc(zone); unsigned long uninitialized_var(buddy_pfn); - struct page *buddy; + unsigned long combined_pfn; + struct free_area *area; unsigned int max_order; - struct capture_control *capc = task_capc(zone); + struct page *buddy; max_order = min_t(unsigned int, MAX_ORDER, pageblock_order + 1); @@ -979,35 +1010,12 @@ static inline void __free_one_page(struct page *page, done_merging: set_page_order(page, order); - /* - * If this is not the largest possible page, check if the buddy - * of the next-highest order is free. If it is, it's possible - * that pages are being freed that will coalesce soon. In case, - * that is happening, add the free page to the tail of the list - * so it's less likely to be used soon and more likely to be merged - * as a higher order page - */ - if ((order < MAX_ORDER-2) && pfn_valid_within(buddy_pfn) - && !is_shuffle_order(order)) { - struct page *higher_page, *higher_buddy; - combined_pfn = buddy_pfn & pfn; - higher_page = page + (combined_pfn - pfn); - buddy_pfn = __find_buddy_pfn(combined_pfn, order + 1); - higher_buddy = higher_page + (buddy_pfn - combined_pfn); - if (pfn_valid_within(buddy_pfn) && - page_is_buddy(higher_page, higher_buddy, order + 1)) { - add_to_free_area_tail(page, &zone->free_area[order], - migratetype); - return; - } - } - - if (is_shuffle_order(order)) - add_to_free_area_random(page, &zone->free_area[order], - migratetype); + area = &zone->free_area[order]; + if (is_shuffle_order(order) ? shuffle_pick_tail() : + buddy_merge_likely(pfn, buddy_pfn, page, order)) + add_to_free_area_tail(page, area, migratetype); else - add_to_free_area(page, &zone->free_area[order], migratetype); - + add_to_free_area(page, area, migratetype); } /* diff --git a/mm/shuffle.c b/mm/shuffle.c index 3ce12481b1dc..345cb4347455 100644 --- a/mm/shuffle.c +++ b/mm/shuffle.c @@ -4,7 +4,6 @@ #include #include #include -#include #include #include "internal.h" #include "shuffle.h" @@ -183,25 +182,34 @@ void __meminit __shuffle_free_memory(pg_data_t *pgdat) shuffle_zone(z); } -void add_to_free_area_random(struct page *page, struct free_area *area, - int migratetype) +struct batched_bit_entropy { + unsigned long entropy_bool; + int position; +}; + +static DEFINE_PER_CPU(struct batched_bit_entropy, batched_entropy_bool); + +bool __shuffle_pick_tail(void) { - static u64 rand; - static u8 rand_bits; + struct batched_bit_entropy *batch; + unsigned long entropy; + int position; /* - * The lack of locking is deliberate. If 2 threads race to - * update the rand state it just adds to the entropy. + * We shouldn't need to disable IRQs as the only caller is + * __free_one_page and it should only be called with the zone lock + * held and either from IRQ context or with local IRQs disabled. */ - if (rand_bits == 0) { - rand_bits = 64; - rand = get_random_u64(); + batch = raw_cpu_ptr(&batched_entropy_bool); + position = batch->position; + + if (--position < 0) { + batch->entropy_bool = get_random_long(); + position = BITS_PER_LONG - 1; } - if (rand & 1) - add_to_free_area(page, area, migratetype); - else - add_to_free_area_tail(page, area, migratetype); - rand_bits--; - rand >>= 1; + batch->position = position; + entropy = batch->entropy_bool; + + return 1ul & (entropy >> position); } diff --git a/mm/shuffle.h b/mm/shuffle.h index 777a257a0d2f..0723eb97f22f 100644 --- a/mm/shuffle.h +++ b/mm/shuffle.h @@ -3,6 +3,7 @@ #ifndef _MM_SHUFFLE_H #define _MM_SHUFFLE_H #include +#include /* * SHUFFLE_ENABLE is called from the command line enabling path, or by @@ -22,6 +23,7 @@ enum mm_shuffle_ctl { DECLARE_STATIC_KEY_FALSE(page_alloc_shuffle_key); extern void page_alloc_shuffle(enum mm_shuffle_ctl ctl); extern void __shuffle_free_memory(pg_data_t *pgdat); +extern bool __shuffle_pick_tail(void); static inline void shuffle_free_memory(pg_data_t *pgdat) { if (!static_branch_unlikely(&page_alloc_shuffle_key)) @@ -43,6 +45,11 @@ static inline bool is_shuffle_order(int order) return false; return order >= SHUFFLE_ORDER; } + +static inline bool shuffle_pick_tail(void) +{ + return __shuffle_pick_tail(); +} #else static inline void shuffle_free_memory(pg_data_t *pgdat) { @@ -60,5 +67,10 @@ static inline bool is_shuffle_order(int order) { return false; } + +static inline bool shuffle_pick_tail(void) +{ + return false; +} #endif #endif /* _MM_SHUFFLE_H */