From patchwork Wed Dec 21 06:52:24 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liang Li X-Patchwork-Id: 9482617 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 2B9BA60237 for ; Wed, 21 Dec 2016 06:59:12 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1CB4D2808F for ; Wed, 21 Dec 2016 06:59:12 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 101E9280FC; Wed, 21 Dec 2016 06:59:12 +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 lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 87A342808F for ; Wed, 21 Dec 2016 06:59:11 +0000 (UTC) Received: from localhost ([::1]:55475 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cJarm-0007TQ-Pw for patchwork-qemu-devel@patchwork.kernel.org; Wed, 21 Dec 2016 01:59:10 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52797) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cJarJ-0007Qj-HX for qemu-devel@nongnu.org; Wed, 21 Dec 2016 01:58:42 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cJarG-0006eh-FB for qemu-devel@nongnu.org; Wed, 21 Dec 2016 01:58:41 -0500 Received: from mga11.intel.com ([192.55.52.93]:25760) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cJarG-0006dm-2d for qemu-devel@nongnu.org; Wed, 21 Dec 2016 01:58:38 -0500 Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga102.fm.intel.com with ESMTP; 20 Dec 2016 22:58:36 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,382,1477983600"; d="scan'208";a="205236953" Received: from ll.sh.intel.com (HELO localhost) ([10.239.13.123]) by fmsmga004.fm.intel.com with ESMTP; 20 Dec 2016 22:58:33 -0800 From: Liang Li To: kvm@vger.kernel.org Date: Wed, 21 Dec 2016 14:52:24 +0800 Message-Id: <1482303148-22059-2-git-send-email-liang.z.li@intel.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1482303148-22059-1-git-send-email-liang.z.li@intel.com> References: <1482303148-22059-1-git-send-email-liang.z.li@intel.com> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 192.55.52.93 Subject: [Qemu-devel] [PATCH v6 kernel 1/5] virtio-balloon: rework deflate to add page to a list X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: aarcange@redhat.com, virtio-dev@lists.oasis-open.org, cornelia.huck@de.ibm.com, quintela@redhat.com, dave.hansen@intel.com, linux-kernel@vger.kernel.org, mst@redhat.com, david@redhat.com, qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, linux-mm@kvack.org, amit.shah@redhat.com, pbonzini@redhat.com, Liang Li , dgilbert@redhat.com Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" 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 {pfn|length} array instead of a PFN array. Comparing with PFN array, {pfn|length} array can present more pages and is fit for batch processing. This patch saves the deflated pages to a list instead of the PFN array, which will allow faster notifications using the {pfn|length} 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 Cc: Andrea Arcangeli Cc: David Hildenbrand --- 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; }