From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754232AbdHUUWW (ORCPT ); Mon, 21 Aug 2017 16:22:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:2243 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753790AbdHUUWU (ORCPT ); Mon, 21 Aug 2017 16:22:20 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 02C53267CD Authentication-Results: ext-mx06.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx06.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=mst@redhat.com Date: Mon, 21 Aug 2017 23:22:17 +0300 From: "Michael S. Tsirkin" To: Wei Wang Cc: virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org, qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, linux-mm@kvack.org, mhocko@kernel.org, akpm@linux-foundation.org, mawilcox@microsoft.com, david@redhat.com, cornelia.huck@de.ibm.com, mgorman@techsingularity.net, aarcange@redhat.com, amit.shah@redhat.com, pbonzini@redhat.com, willy@infradead.org, liliang.opensource@gmail.com, yang.zhang.wz@gmail.com, quan.xu@aliyun.com Subject: Re: [PATCH v14 3/5] virtio-balloon: VIRTIO_BALLOON_F_SG Message-ID: <20170821232052-mutt-send-email-mst@kernel.org> References: <1502940416-42944-1-git-send-email-wei.w.wang@intel.com> <1502940416-42944-4-git-send-email-wei.w.wang@intel.com> <20170818051451-mutt-send-email-mst@kernel.org> <599699AF.1090705@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <599699AF.1090705@intel.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Mon, 21 Aug 2017 20:22:20 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 18, 2017 at 03:39:27PM +0800, Wei Wang wrote: > On 08/18/2017 10:22 AM, Michael S. Tsirkin wrote: > > +static void send_balloon_page_sg(struct virtio_balloon *vb, > > + struct virtqueue *vq, > > + void *addr, > > + uint32_t size) > > +{ > > + unsigned int len; > > + int ret; > > + > > + do { > > + ret = add_one_sg(vq, addr, size); > > + virtqueue_kick(vq); > > + wait_event(vb->acked, virtqueue_get_buf(vq, &len)); > > + /* > > + * It is uncommon to see the vq is full, because the sg is sent > > + * one by one and the device is able to handle it in time. But > > + * if that happens, we go back to retry after an entry gets > > + * released. > > + */ > > Why send one by one though? Why not batch some s/gs and wait for all > > of them to be completed? If memory if fragmented, waiting every time is > > worse than what we have now (VIRTIO_BALLOON_ARRAY_PFNS_MAX at a time). > > > > OK, I'll do batching in some fashion. > > > Best, > Wei > > btw you need to address the build errors that kbot has found. -- MST