From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758109Ab3IBDPZ (ORCPT ); Sun, 1 Sep 2013 23:15:25 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54986 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757963Ab3IBDPY (ORCPT ); Sun, 1 Sep 2013 23:15:24 -0400 Message-ID: <522402C2.9000802@redhat.com> Date: Mon, 02 Sep 2013 11:15:14 +0800 From: Jason Wang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130803 Thunderbird/17.0.8 MIME-Version: 1.0 To: Sergei Shtylyov CC: mst@redhat.com, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH V2 4/6] vhost_net: determine whether or not to use zerocopy at one time References: <1377836962-49780-1-git-send-email-jasowang@redhat.com> <1377836962-49780-5-git-send-email-jasowang@redhat.com> <5220E606.8010008@cogentembedded.com> In-Reply-To: <5220E606.8010008@cogentembedded.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/31/2013 02:35 AM, Sergei Shtylyov wrote: > Hello. > > On 08/30/2013 08:29 AM, Jason Wang wrote: > >> Currently, even if the packet length is smaller than >> VHOST_GOODCOPY_LEN, if >> upend_idx != done_idx we still set zcopy_used to true and rollback >> this choice >> later. This could be avoided by determine zerocopy once by checking all >> conditions at one time before. > >> Signed-off-by: Jason Wang >> --- >> drivers/vhost/net.c | 46 >> +++++++++++++++++++--------------------------- >> 1 files changed, 19 insertions(+), 27 deletions(-) > >> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c >> index 8a6dd0d..ff60c2a 100644 >> --- a/drivers/vhost/net.c >> +++ b/drivers/vhost/net.c >> @@ -404,43 +404,35 @@ static void handle_tx(struct vhost_net *net) >> iov_length(nvq->hdr, s), hdr_size); >> break; >> } >> - zcopy_used = zcopy && (len >= VHOST_GOODCOPY_LEN || >> - nvq->upend_idx != nvq->done_idx); >> + >> + zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN >> + && (nvq->upend_idx + 1) % UIO_MAXIOV != nvq->done_idx >> + && vhost_net_tx_select_zcopy(net); > > Could you leave && on a first of two lines, matching the previous > style? > ok. >> >> /* use msg_control to pass vhost zerocopy ubuf info to skb */ >> if (zcopy_used) { >> + struct ubuf_info *ubuf; >> + ubuf = nvq->ubuf_info + nvq->upend_idx; >> + >> vq->heads[nvq->upend_idx].id = head; > [...] >> + vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS; >> + ubuf->callback = vhost_zerocopy_callback; >> + ubuf->ctx = nvq->ubufs; >> + ubuf->desc = nvq->upend_idx; >> + msg.msg_control = ubuf; >> + msg.msg_controllen = sizeof(ubuf); > > 'sizeof(ubuf)' where 'ubuf' is a pointer? Are you sure it shouldn't > be 'sizeof(*ubuf)'? Yes, pointer is sufficiet. Vhost allocate an arrays of ubuf and tun/macvtap just need a reference of it. > > WBR, Sergei > > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html