From patchwork Fri Oct 21 06:48:20 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Li, Liang Z" X-Patchwork-Id: 684923 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3t0c850wS1z9rxm for ; Fri, 21 Oct 2016 18:03:01 +1100 (AEDT) Received: from localhost ([::1]:59051 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bxTr0-0003C9-4g for incoming@patchwork.ozlabs.org; Fri, 21 Oct 2016 03:02:58 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42181) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bxToz-0001Zd-Oa for qemu-devel@nongnu.org; Fri, 21 Oct 2016 03:00:55 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bxTow-0008CS-NM for qemu-devel@nongnu.org; Fri, 21 Oct 2016 03:00:53 -0400 Received: from mga07.intel.com ([134.134.136.100]:38249) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1bxTow-0008BC-D3 for qemu-devel@nongnu.org; Fri, 21 Oct 2016 03:00:50 -0400 Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga105.jf.intel.com with ESMTP; 21 Oct 2016 00:00:49 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos; i="5.31,375,1473145200"; d="scan'208"; a="1073582884" Received: from ll.sh.intel.com (HELO localhost) ([10.239.13.123]) by fmsmga002.fm.intel.com with ESMTP; 21 Oct 2016 00:00:48 -0700 From: Liang Li To: qemu-devel@nongnu.org Date: Fri, 21 Oct 2016 14:48:20 +0800 Message-Id: <1477032504-12745-3-git-send-email-liang.z.li@intel.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1477032504-12745-1-git-send-email-liang.z.li@intel.com> References: <1477032504-12745-1-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: 134.134.136.100 Subject: [Qemu-devel] [PATCH qemu v3 2/6] virtio-balloon: speed up inflating & deflating process 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: virtio-dev@lists.oasis-open.org, thuth@redhat.com, Liang Li , kvm@vger.kernel.org, quintela@redhat.com, mst@redhat.com, dgilbert@redhat.com, dave.hansen@intel.com, amit.shah@redhat.com, pbonzini@redhat.com Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" The implementation of the current virtio-balloon is not very efficient, the time spends on different stages of inflating the balloon to 7GB of a 8GB idle guest: a. allocating pages (6.5%) b. sending PFNs to host (68.3%) c. address translation (6.1%) d. madvise (19%) It takes about 4126ms for the inflating process to complete. Debugging shows that the bottle neck are the stage b and stage d. If using a bitmap to send the page info instead of the PFNs, we can reduce the overhead in stage b quite a lot. Furthermore, we can do the address translation and call madvise() with a bulk of RAM pages, instead of the current page per page way, the overhead of stage c and stage d can also be reduced a lot. This patch is the kernel side implementation which is intended to speed up the inflating & deflating process by adding a new feature to the virtio-balloon device. With this new feature, inflating the balloon to 7GB of a 8GB idle guest only takes 590ms, the performance improvement is about 85%. TODO: optimize stage a by allocating/freeing a chunk of pages instead of a single page at a time. Signed-off-by: Liang Li Suggested-by: Michael S. Tsirkin --- hw/virtio/virtio-balloon.c | 144 ++++++++++++++++++++++++++++++++++++++------- 1 file changed, 123 insertions(+), 21 deletions(-) diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c index 1d77028..3fa80a4 100644 --- a/hw/virtio/virtio-balloon.c +++ b/hw/virtio/virtio-balloon.c @@ -52,6 +52,77 @@ static const char *balloon_stat_names[] = { [VIRTIO_BALLOON_S_NR] = NULL }; +static void do_balloon_bulk_pages(ram_addr_t base_pfn, uint16_t page_shift, + unsigned long len, bool deflate) +{ + ram_addr_t size, processed, chunk, base; + MemoryRegionSection section = {.mr = NULL}; + + size = len << page_shift; + base = base_pfn << page_shift; + + for (processed = 0; processed < size; processed += chunk) { + chunk = size - processed; + while (chunk >= TARGET_PAGE_SIZE) { + section = memory_region_find(get_system_memory(), + base + processed, chunk); + if (!section.mr) { + chunk = QEMU_ALIGN_DOWN(chunk / 2, TARGET_PAGE_SIZE); + } else { + break; + } + } + + if (section.mr && + (int128_nz(section.size) && memory_region_is_ram(section.mr))) { + void *addr = section.offset_within_region + + memory_region_get_ram_ptr(section.mr); + qemu_madvise(addr, chunk, + deflate ? QEMU_MADV_WILLNEED : QEMU_MADV_DONTNEED); + } else { + qemu_log_mask(LOG_GUEST_ERROR, + "Invalid guest RAM range [0x%lx, 0x%lx]\n", + base + processed, chunk); + chunk = TARGET_PAGE_SIZE; + } + } +} + +static void balloon_bulk_pages(struct balloon_bmap_hdr *hdr, + unsigned long *bitmap, bool deflate) +{ + ram_addr_t base_pfn = hdr->start_pfn; + uint16_t page_shift = hdr->page_shift; + unsigned long len = hdr->bmap_len; + unsigned long current = 0, end = len * BITS_PER_BYTE; + + if (!qemu_balloon_is_inhibited() && (!kvm_enabled() || + kvm_has_sync_mmu())) { + while (current < end) { + unsigned long one = find_next_bit(bitmap, end, current); + + if (one < end) { + unsigned long pages, zero; + + zero = find_next_zero_bit(bitmap, end, one + 1); + if (zero >= end) { + pages = end - one; + } else { + pages = zero - one; + } + + if (pages) { + do_balloon_bulk_pages(base_pfn + one, page_shift, + pages, deflate); + } + current = one + pages; + } else { + current = one; + } + } + } +} + /* * reset_stats - Mark all items in the stats array as unset * @@ -72,6 +143,13 @@ static bool balloon_stats_supported(const VirtIOBalloon *s) return virtio_vdev_has_feature(vdev, VIRTIO_BALLOON_F_STATS_VQ); } +static bool balloon_page_bitmap_supported(const VirtIOBalloon *s) +{ + VirtIODevice *vdev = VIRTIO_DEVICE(s); + + return virtio_vdev_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_BITMAP); +} + static bool balloon_stats_enabled(const VirtIOBalloon *s) { return s->stats_poll_interval > 0; @@ -213,32 +291,54 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq) for (;;) { size_t offset = 0; uint32_t pfn; + elem = virtqueue_pop(vq, sizeof(VirtQueueElement)); if (!elem) { return; } - while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) == 4) { - ram_addr_t pa; - ram_addr_t addr; - int p = virtio_ldl_p(vdev, &pfn); - - pa = (ram_addr_t) p << VIRTIO_BALLOON_PFN_SHIFT; - offset += 4; - - /* FIXME: remove get_system_memory(), but how? */ - section = memory_region_find(get_system_memory(), pa, 1); - if (!int128_nz(section.size) || !memory_region_is_ram(section.mr)) - continue; - - trace_virtio_balloon_handle_output(memory_region_name(section.mr), - pa); - /* Using memory_region_get_ram_ptr is bending the rules a bit, but - should be OK because we only want a single page. */ - addr = section.offset_within_region; - balloon_page(memory_region_get_ram_ptr(section.mr) + addr, - !!(vq == s->dvq)); - memory_region_unref(section.mr); + if (balloon_page_bitmap_supported(s)) { + struct balloon_bmap_hdr hdr; + uint64_t bmap_len; + + iov_to_buf(elem->out_sg, elem->out_num, offset, &hdr, sizeof(hdr)); + offset += sizeof(hdr); + + bmap_len = hdr.bmap_len; + if (bmap_len > 0) { + unsigned long *bitmap = bitmap_new(bmap_len * BITS_PER_BYTE); + iov_to_buf(elem->out_sg, elem->out_num, offset, + bitmap, bmap_len); + + balloon_bulk_pages(&hdr, bitmap, !!(vq == s->dvq)); + g_free(bitmap); + } + } else { + while (iov_to_buf(elem->out_sg, elem->out_num, offset, + &pfn, 4) == 4) { + ram_addr_t pa; + ram_addr_t addr; + int p = virtio_ldl_p(vdev, &pfn); + + pa = (ram_addr_t) p << VIRTIO_BALLOON_PFN_SHIFT; + offset += 4; + + /* FIXME: remove get_system_memory(), but how? */ + section = memory_region_find(get_system_memory(), pa, 1); + if (!int128_nz(section.size) || + !memory_region_is_ram(section.mr)) { + continue; + } + + trace_virtio_balloon_handle_output(memory_region_name( + section.mr), pa); + /* Using memory_region_get_ram_ptr is bending the rules a bit, + * but should be OK because we only want a single page. */ + addr = section.offset_within_region; + balloon_page(memory_region_get_ram_ptr(section.mr) + addr, + !!(vq == s->dvq)); + memory_region_unref(section.mr); + } } virtqueue_push(vq, elem, offset); @@ -500,6 +600,8 @@ static const VMStateDescription vmstate_virtio_balloon = { static Property virtio_balloon_properties[] = { DEFINE_PROP_BIT("deflate-on-oom", VirtIOBalloon, host_features, VIRTIO_BALLOON_F_DEFLATE_ON_OOM, false), + DEFINE_PROP_BIT("page-bitmap", VirtIOBalloon, host_features, + VIRTIO_BALLOON_F_PAGE_BITMAP, true), DEFINE_PROP_END_OF_LIST(), };