From patchwork Wed Nov 30 08:43:13 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liang Li X-Patchwork-Id: 9454083 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 9E1EA60757 for ; Wed, 30 Nov 2016 11:33:11 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8112928470 for ; Wed, 30 Nov 2016 11:33:11 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 7F7D328468; Wed, 30 Nov 2016 11:33:11 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1A1C128478 for ; Wed, 30 Nov 2016 11:33:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757483AbcK3I6R (ORCPT ); Wed, 30 Nov 2016 03:58:17 -0500 Received: from mga04.intel.com ([192.55.52.120]:44300 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757475AbcK3I6N (ORCPT ); Wed, 30 Nov 2016 03:58:13 -0500 Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga104.fm.intel.com with ESMTP; 30 Nov 2016 00:58:12 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,573,1473145200"; d="scan'208";a="197326162" Received: from ll.sh.intel.com (HELO localhost) ([10.239.13.123]) by fmsmga004.fm.intel.com with ESMTP; 30 Nov 2016 00:58:07 -0800 From: Liang Li To: kvm@vger.kernel.org Cc: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, virtio-dev@lists.oasis-open.org, qemu-devel@nongnu.org, quintela@redhat.com, dgilbert@redhat.com, dave.hansen@intel.com, mst@redhat.com, jasowang@redhat.com, kirill.shutemov@linux.intel.com, akpm@linux-foundation.org, mhocko@suse.com, pbonzini@redhat.com, Liang Li , Cornelia Huck , Amit Shah Subject: [PATCH kernel v5 1/5] virtio-balloon: rework deflate to add page to a list Date: Wed, 30 Nov 2016 16:43:13 +0800 Message-Id: <1480495397-23225-2-git-send-email-liang.z.li@intel.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1480495397-23225-1-git-send-email-liang.z.li@intel.com> References: <1480495397-23225-1-git-send-email-liang.z.li@intel.com> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP When doing the inflating/deflating operation, the current virtio-balloon implementation uses an array to save 256 PFNS, then send these PFNS to host through virtio and process each PFN one by one. This way is not efficient when inflating/deflating a large mount of memory because too many times of the following operations: 1. Virtio data transmission 2. Page allocate/free 3. Address translation(GPA->HVA) 4. madvise The over head of these operations will consume a lot of CPU cycles and will take a long time to complete, it may impact the QoS of the guest as well as the host. The overhead will be reduced a lot if batch processing is used. E.g. If there are several pages whose address are physical contiguous in the guest, these bulk pages can be processed in one operation. The main idea for the optimization is to reduce the above operations as much as possible. And it can be achieved by using a bitmap instead of an PFN array. Comparing with PFN array, for a specific size buffer, bitmap can present more pages, which is very important for batch processing. Using bitmap instead of PFN is not very helpful when inflating/deflating a small mount of pages, in this case, using PFNs is better. But using bitmap will not impact the QoS of guest or host heavily because the operation will be completed very soon for a small mount of pages, and we will use some methods to make sure the efficiency not drop too much. This patch saves the deflated pages to a list instead of the PFN array, which will allow faster notifications using a bitmap down the road. balloon_pfn_to_page() can be removed because it's useless. Signed-off-by: Liang Li Signed-off-by: Michael S. Tsirkin Cc: Paolo Bonzini Cc: Cornelia Huck Cc: Amit Shah Cc: Dave Hansen --- drivers/virtio/virtio_balloon.c | 22 ++++++++-------------- 1 file changed, 8 insertions(+), 14 deletions(-) diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 181793f..f59cb4f 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -103,12 +103,6 @@ static u32 page_to_balloon_pfn(struct page *page) return pfn * VIRTIO_BALLOON_PAGES_PER_PAGE; } -static struct page *balloon_pfn_to_page(u32 pfn) -{ - BUG_ON(pfn % VIRTIO_BALLOON_PAGES_PER_PAGE); - return pfn_to_page(pfn / VIRTIO_BALLOON_PAGES_PER_PAGE); -} - static void balloon_ack(struct virtqueue *vq) { struct virtio_balloon *vb = vq->vdev->priv; @@ -181,18 +175,16 @@ static unsigned fill_balloon(struct virtio_balloon *vb, size_t num) return num_allocated_pages; } -static void release_pages_balloon(struct virtio_balloon *vb) +static void release_pages_balloon(struct virtio_balloon *vb, + struct list_head *pages) { - unsigned int i; - struct page *page; + struct page *page, *next; - /* Find pfns pointing at start of each page, get pages and free them. */ - for (i = 0; i < vb->num_pfns; i += VIRTIO_BALLOON_PAGES_PER_PAGE) { - page = balloon_pfn_to_page(virtio32_to_cpu(vb->vdev, - vb->pfns[i])); + list_for_each_entry_safe(page, next, pages, lru) { if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) adjust_managed_page_count(page, 1); + list_del(&page->lru); put_page(page); /* balloon reference */ } } @@ -202,6 +194,7 @@ static unsigned leak_balloon(struct virtio_balloon *vb, size_t num) unsigned num_freed_pages; struct page *page; struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; + LIST_HEAD(pages); /* We can only do one array worth at a time. */ num = min(num, ARRAY_SIZE(vb->pfns)); @@ -215,6 +208,7 @@ static unsigned leak_balloon(struct virtio_balloon *vb, size_t num) if (!page) break; set_page_pfns(vb, vb->pfns + vb->num_pfns, page); + list_add(&page->lru, &pages); vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE; } @@ -226,7 +220,7 @@ static unsigned leak_balloon(struct virtio_balloon *vb, size_t num) */ if (vb->num_pfns != 0) tell_host(vb, vb->deflate_vq); - release_pages_balloon(vb); + release_pages_balloon(vb, &pages); mutex_unlock(&vb->balloon_lock); return num_freed_pages; }