From patchwork Wed Jul 17 10:52:47 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jason Wang X-Patchwork-Id: 11047635 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 83F36912 for ; Wed, 17 Jul 2019 10:53:44 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 735042872A for ; Wed, 17 Jul 2019 10:53:44 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6727528737; Wed, 17 Jul 2019 10:53:44 +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=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, 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 1E6232872A for ; Wed, 17 Jul 2019 10:53:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731637AbfGQKxi (ORCPT ); Wed, 17 Jul 2019 06:53:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37620 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731586AbfGQKxh (ORCPT ); Wed, 17 Jul 2019 06:53:37 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 95C1659474; Wed, 17 Jul 2019 10:53:37 +0000 (UTC) Received: from hp-dl380pg8-01.lab.eng.pek2.redhat.com (hp-dl380pg8-01.lab.eng.pek2.redhat.com [10.73.8.10]) by smtp.corp.redhat.com (Postfix) with ESMTP id AB25B1001DC0; Wed, 17 Jul 2019 10:53:34 +0000 (UTC) From: Jason Wang To: mst@redhat.com, jasowang@redhat.com Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, jfreimann@redhat.com, tiwei.bie@intel.com, maxime.coquelin@redhat.com Subject: [PATCH V3 07/15] vhost_net: calculate last used length once for mergeable buffer Date: Wed, 17 Jul 2019 06:52:47 -0400 Message-Id: <20190717105255.63488-8-jasowang@redhat.com> In-Reply-To: <20190717105255.63488-1-jasowang@redhat.com> References: <20190717105255.63488-1-jasowang@redhat.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Wed, 17 Jul 2019 10:53:37 +0000 (UTC) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This patch tries to calculate last used length once instead of twice. This can help to convert to use shadow used ring API for RX. Signed-off-by: Jason Wang --- drivers/vhost/net.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index cf47e6e348f4..1a67f889cbc1 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -1065,12 +1065,12 @@ static int get_rx_bufs(struct vhost_virtqueue *vq, } heads[headcount].id = cpu_to_vhost32(vq, d); len = iov_length(vq->iov + seg, in); - heads[headcount].len = cpu_to_vhost32(vq, len); datalen -= len; + heads[headcount].len = cpu_to_vhost32(vq, + datalen >= 0 ? len : len + datalen); ++headcount; seg += in; } - heads[headcount - 1].len = cpu_to_vhost32(vq, len + datalen); *iovcount = seg; if (unlikely(log)) *log_num = nlogs;