From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 53F58C433E1 for ; Thu, 16 Jul 2020 07:32:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3C346206F5 for ; Thu, 16 Jul 2020 07:32:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728346AbgGPHcn convert rfc822-to-8bit (ORCPT ); Thu, 16 Jul 2020 03:32:43 -0400 Received: from out30-43.freemail.mail.aliyun.com ([115.124.30.43]:37076 "EHLO out30-43.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726069AbgGPHcm (ORCPT ); Thu, 16 Jul 2020 03:32:42 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R131e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01355;MF=teawaterz@linux.alibaba.com;NM=1;PH=DS;RN=10;SR=0;TI=SMTPD_---0U2sTlwu_1594884751; Received: from 127.0.0.1(mailfrom:teawaterz@linux.alibaba.com fp:SMTPD_---0U2sTlwu_1594884751) by smtp.aliyun-inc.com(127.0.0.1); Thu, 16 Jul 2020 15:32:37 +0800 Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 13.4 \(3608.80.23.2.2\)) Subject: Re: [virtio-dev] [RFC for qemu v4 2/2] virtio_balloon: Add dcvq to deflate continuous pages From: teawater In-Reply-To: <20200716023910-mutt-send-email-mst@kernel.org> Date: Thu, 16 Jul 2020 15:32:30 +0800 Cc: Hui Zhu , david@redhat.com, jasowang@redhat.com, akpm@linux-foundation.org, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, qemu-devel@nongnu.org, virtio-dev@lists.oasis-open.org Content-Transfer-Encoding: 8BIT Message-Id: <4F64B592-03CF-46F5-B761-78B4EBA5028E@linux.alibaba.com> References: <1594867315-8626-1-git-send-email-teawater@gmail.com> <1594867315-8626-6-git-send-email-teawater@gmail.com> <20200716023910-mutt-send-email-mst@kernel.org> To: "Michael S. Tsirkin" X-Mailer: Apple Mail (2.3608.80.23.2.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > 2020年7月16日 14:39，Michael S. Tsirkin 写道： > > On Thu, Jul 16, 2020 at 10:41:55AM +0800, Hui Zhu wrote: >> This commit adds a vq dcvq to deflate continuous pages. >> When VIRTIO_BALLOON_F_CONT_PAGES is set, try to get continuous pages >> from icvq and use madvise MADV_WILLNEED with the pages. >> >> Signed-off-by: Hui Zhu > > This is arguably something to benchmark. Does guest benefit > from MADV_WILLNEED or loose performance? MADV_WILLNEED will call madvise_willneed in the host kernel. madvise_willneed will schedule all required I/O operations (swap in or vfs_fadvise POSIX_FADV_WILLNEED) of the address. But the pages of the balloon are released by MADV_DONTNEED. So I think MADV_WILLNEED will not affect the performance of the guest in the most of situations. Best, Hui > >> --- >> hw/virtio/virtio-balloon.c | 14 +++++++++----- >> include/hw/virtio/virtio-balloon.h | 2 +- >> 2 files changed, 10 insertions(+), 6 deletions(-) >> >> diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c >> index d36a5c8..165adf7 100644 >> --- a/hw/virtio/virtio-balloon.c >> +++ b/hw/virtio/virtio-balloon.c >> @@ -138,7 +138,8 @@ static void balloon_inflate_page(VirtIOBalloon *balloon, >> } >> >> static void balloon_deflate_page(VirtIOBalloon *balloon, >> - MemoryRegion *mr, hwaddr mr_offset) >> + MemoryRegion *mr, hwaddr mr_offset, >> + size_t size) >> { >> void *addr = memory_region_get_ram_ptr(mr) + mr_offset; >> ram_addr_t rb_offset; >> @@ -153,10 +154,11 @@ static void balloon_deflate_page(VirtIOBalloon *balloon, >> rb_page_size = qemu_ram_pagesize(rb); >> >> host_addr = (void *)((uintptr_t)addr & ~(rb_page_size - 1)); >> + size &= ~(rb_page_size - 1); >> >> /* When a page is deflated, we hint the whole host page it lives >> * on, since we can't do anything smaller */ >> - ret = qemu_madvise(host_addr, rb_page_size, QEMU_MADV_WILLNEED); >> + ret = qemu_madvise(host_addr, size, QEMU_MADV_WILLNEED); >> if (ret != 0) { >> warn_report("Couldn't MADV_WILLNEED on balloon deflate: %s", >> strerror(errno)); >> @@ -354,7 +356,7 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq) >> pa = (hwaddr) p << VIRTIO_BALLOON_PFN_SHIFT; >> offset += 4; >> >> - if (vq == s->icvq) { >> + if (vq == s->icvq || vq == s->dcvq) { >> uint32_t psize_ptr; >> if (iov_to_buf(elem->out_sg, elem->out_num, offset, &psize_ptr, 4) != 4) { >> break; >> @@ -383,8 +385,9 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq) >> balloon_inflate_page(s, section.mr, >> section.offset_within_region, >> psize, &pbp); >> - } else if (vq == s->dvq) { >> - balloon_deflate_page(s, section.mr, section.offset_within_region); >> + } else if (vq == s->dvq || vq == s->dcvq) { >> + balloon_deflate_page(s, section.mr, section.offset_within_region, >> + psize); >> } else { >> g_assert_not_reached(); >> } >> @@ -838,6 +841,7 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp) >> >> if (virtio_has_feature(s->host_features, VIRTIO_BALLOON_F_CONT_PAGES)) { >> s->icvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output); >> + s->dcvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output); >> } >> >> reset_stats(s); >> diff --git a/include/hw/virtio/virtio-balloon.h b/include/hw/virtio/virtio-balloon.h >> index 6a2514d..848a7fb 100644 >> --- a/include/hw/virtio/virtio-balloon.h >> +++ b/include/hw/virtio/virtio-balloon.h >> @@ -42,7 +42,7 @@ enum virtio_balloon_free_page_report_status { >> >> typedef struct VirtIOBalloon { >> VirtIODevice parent_obj; >> - VirtQueue *ivq, *dvq, *svq, *free_page_vq, *icvq; >> + VirtQueue *ivq, *dvq, *svq, *free_page_vq, *icvq, *dcvq; >> uint32_t free_page_report_status; >> uint32_t num_pages; >> uint32_t actual; >> -- >> 2.7.4 > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org > For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org