Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757439AbcCCKxV (ORCPT ); Thu, 3 Mar 2016 05:53:21 -0500 Received: from mga04.intel.com ([192.55.52.120]:13689 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757407AbcCCKxO (ORCPT ); Thu, 3 Mar 2016 05:53:14 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.22,532,1449561600"; d="scan'208";a="59026876" From: Liang Li To: mst@redhat.com, linux-kernel@vger.kernel.org Cc: akpm@linux-foundation.org, pbonzini@redhat.com, rth@twiddle.net, ehabkost@redhat.com, quintela@redhat.com, amit.shah@redhat.com, qemu-devel@nongnu.org, linux-mm@kvack.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, dgilbert@redhat.com, Liang Li Subject: [RFC kernel 1/2] mm: Add the functions used to get free pages information Date: Thu, 3 Mar 2016 18:46:58 +0800 Message-Id: <1457002019-15998-2-git-send-email-liang.z.li@intel.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1457002019-15998-1-git-send-email-liang.z.li@intel.com> References: <1457002019-15998-1-git-send-email-liang.z.li@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2175 Lines: 83 get_total_pages_count() tries to get the page count of the system RAM. get_free_pages() is intend to construct a free pages bitmap by traversing the free_list. The free pages information will be sent to QEMU through virtio and used for live migration optimization. Signed-off-by: Liang Li --- mm/page_alloc.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 838ca8bb..81922e6 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3860,6 +3860,63 @@ void show_free_areas(unsigned int filter) show_swap_cache_info(); } +#define PFN_4G (0x100000000 >> PAGE_SHIFT) + +unsigned long get_total_pages_count(unsigned long low_mem) +{ + if (max_pfn >= PFN_4G) { + unsigned long pfn_gap = PFN_4G - (low_mem >> PAGE_SHIFT); + + return max_pfn - pfn_gap; + } else + return max_pfn; +} +EXPORT_SYMBOL(get_total_pages_count); + +static void mark_free_pages_bitmap(struct zone *zone, + unsigned long *free_page_bitmap, unsigned long pfn_gap) +{ + unsigned long pfn, flags, i; + unsigned int order, t; + struct list_head *curr; + + if (zone_is_empty(zone)) + return; + + spin_lock_irqsave(&zone->lock, flags); + + for_each_migratetype_order(order, t) { + list_for_each(curr, &zone->free_area[order].free_list[t]) { + + pfn = page_to_pfn(list_entry(curr, struct page, lru)); + for (i = 0; i < (1UL << order); i++) { + if ((pfn + i) >= PFN_4G) + set_bit_le(pfn + i - pfn_gap, + free_page_bitmap); + else + set_bit_le(pfn + i, free_page_bitmap); + } + } + } + + spin_unlock_irqrestore(&zone->lock, flags); +} + +void get_free_pages(unsigned long *free_page_bitmap, + unsigned long *free_pages_count, + unsigned long low_mem) +{ + struct zone *zone; + unsigned long pfn_gap; + + pfn_gap = PFN_4G - (low_mem >> PAGE_SHIFT); + for_each_populated_zone(zone) + mark_free_pages_bitmap(zone, free_page_bitmap, pfn_gap); + + *free_pages_count = global_page_state(NR_FREE_PAGES); +} +EXPORT_SYMBOL(get_free_pages); + static void zoneref_set_zone(struct zone *zone, struct zoneref *zoneref) { zoneref->zone = zone; -- 1.8.3.1