From patchwork Wed Jan 11 08:48:40 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liang Li X-Patchwork-Id: 9509519 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 E6AAB6075C for ; Wed, 11 Jan 2017 08:56:17 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id DB430284F3 for ; Wed, 11 Jan 2017 08:56:17 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D0351285B0; Wed, 11 Jan 2017 08:56:17 +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=ham 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 46039284F3 for ; Wed, 11 Jan 2017 08:56:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936719AbdAKI4O (ORCPT ); Wed, 11 Jan 2017 03:56:14 -0500 Received: from mga05.intel.com ([192.55.52.43]:11493 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936708AbdAKI4N (ORCPT ); Wed, 11 Jan 2017 03:56:13 -0500 Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga105.fm.intel.com with ESMTP; 11 Jan 2017 00:56:12 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,345,1477983600"; d="scan'208";a="28929024" Received: from ll.sh.intel.com (HELO localhost) ([10.239.13.123]) by orsmga002.jf.intel.com with ESMTP; 11 Jan 2017 00:56:09 -0800 From: Liang Li To: qemu-devel@nongnu.org Cc: kvm@vger.kernel.org, mst@redhat.com, pbonzini@redhat.com, uintela@redhat.com, amit.shah@redhat.com, mtosatti@redhat.com, dgilbert@redhat.com, wei.w.wang@intel.com, dave.hansen@intel.com, Liang Li Subject: [PATCH v4 qemu 2/6] virtio-balloon: speed up inflating & deflating process Date: Wed, 11 Jan 2017 16:48:40 +0800 Message-Id: <1484124524-481-3-git-send-email-liang.z.li@intel.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1484124524-481-1-git-send-email-liang.z.li@intel.com> References: <1484124524-481-1-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 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 {pfn|length} arrays to send the page info instead of the PFNs, we can reduce the overhead in stage b quite a lot. Furthermore, we can do 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 | 142 +++++++++++++++++++++++++++++++++++++-------- 1 file changed, 117 insertions(+), 25 deletions(-) diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c index a705e0e..4ab65ba 100644 --- a/hw/virtio/virtio-balloon.c +++ b/hw/virtio/virtio-balloon.c @@ -31,6 +31,7 @@ #include "hw/virtio/virtio-access.h" #define BALLOON_PAGE_SIZE (1 << VIRTIO_BALLOON_PFN_SHIFT) +#define BALLOON_NR_PFN_MASK ((1 << VIRTIO_BALLOON_NR_PFN_BITS) - 1) static void balloon_page(void *addr, int deflate) { @@ -52,6 +53,69 @@ static const char *balloon_stat_names[] = { [VIRTIO_BALLOON_S_NR] = NULL }; +static void do_balloon_bulk_pages(ram_addr_t base_pfn, + ram_addr_t size, bool deflate) +{ + ram_addr_t processed, chunk, base; + MemoryRegionSection section = {.mr = NULL}; + + base = base_pfn * TARGET_PAGE_SIZE; + + 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) || + memory_region_is_rom(section.mr) || + memory_region_is_romd(section.mr)) { + qemu_log_mask(LOG_GUEST_ERROR, + "Invalid guest RAM range [0x%lx, 0x%lx]\n", + base + processed, chunk); + chunk = TARGET_PAGE_SIZE; + } else { + void *addr = section.offset_within_region + + memory_region_get_ram_ptr(section.mr); + + qemu_madvise(addr, chunk, + deflate ? QEMU_MADV_WILLNEED : QEMU_MADV_DONTNEED); + } + } +} + +static void balloon_bulk_pages(struct virtio_balloon_resp_hdr *hdr, + uint64_t *pages, bool deflate) +{ + ram_addr_t base_pfn; + unsigned long current = 0, nr_pfn, len = hdr->data_len; + uint64_t *range; + + if (!qemu_balloon_is_inhibited() && (!kvm_enabled() || + kvm_has_sync_mmu())) { + while (current < len / sizeof(uint64_t)) { + range = pages + current; + base_pfn = *range >> VIRTIO_BALLOON_NR_PFN_BITS; + nr_pfn = *range & BALLOON_NR_PFN_MASK; + current++; + if (nr_pfn == 0) { + nr_pfn = *(range + 1); + current++; + } + + do_balloon_bulk_pages(base_pfn, nr_pfn * TARGET_PAGE_SIZE, + deflate); + } + } +} + /* * reset_stats - Mark all items in the stats array as unset * @@ -72,6 +136,13 @@ static bool balloon_stats_supported(const VirtIOBalloon *s) return virtio_vdev_has_feature(vdev, VIRTIO_BALLOON_F_STATS_VQ); } +static bool balloon_page_ranges_supported(const VirtIOBalloon *s) +{ + VirtIODevice *vdev = VIRTIO_DEVICE(s); + + return virtio_vdev_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_RANGE); +} + static bool balloon_stats_enabled(const VirtIOBalloon *s) { return s->stats_poll_interval > 0; @@ -218,32 +289,51 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq) 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) || - memory_region_is_rom(section.mr) || - memory_region_is_romd(section.mr)) { - trace_virtio_balloon_bad_addr(pa); - continue; - } + if (balloon_page_ranges_supported(s)) { + struct virtio_balloon_resp_hdr hdr; + uint32_t data_len; + + iov_to_buf(elem->out_sg, elem->out_num, offset, &hdr, sizeof(hdr)); + offset += sizeof(hdr); + + data_len = hdr.data_len; + if (data_len > 0) { + uint64_t *ranges = g_malloc(data_len); - 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); + iov_to_buf(elem->out_sg, elem->out_num, offset, ranges, + data_len); + + balloon_bulk_pages(&hdr, ranges, !!(vq == s->dvq)); + g_free(ranges); + } + } 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) || + memory_region_is_rom(section.mr) || + memory_region_is_romd(section.mr)) { + trace_virtio_balloon_bad_addr(pa); + 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); @@ -505,6 +595,8 @@ 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-ranges", VirtIOBalloon, host_features, + VIRTIO_BALLOON_F_PAGE_RANGE, true), DEFINE_PROP_END_OF_LIST(), };