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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 7D77FC433F5 for ; Fri, 7 Sep 2018 16:13:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1BF772075E for ; Fri, 7 Sep 2018 16:13:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1BF772075E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728016AbeIGUyp (ORCPT ); Fri, 7 Sep 2018 16:54:45 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:40356 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726598AbeIGUyo (ORCPT ); Fri, 7 Sep 2018 16:54:44 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1C2362637B; Fri, 7 Sep 2018 16:13:07 +0000 (UTC) Received: from redhat.com (ovpn-124-199.rdu2.redhat.com [10.10.124.199]) by smtp.corp.redhat.com (Postfix) with SMTP id 932232027EA0; Fri, 7 Sep 2018 16:13:06 +0000 (UTC) Date: Fri, 7 Sep 2018 12:13:06 -0400 From: "Michael S. Tsirkin" To: Jason Wang Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: Re: [PATCH net-next 11/11] vhost_net: batch submitting XDP buffers to underlayer sockets Message-ID: <20180907121148-mutt-send-email-mst@kernel.org> References: <20180906040526.22518-1-jasowang@redhat.com> <20180906040526.22518-12-jasowang@redhat.com> <20180906122857-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Fri, 07 Sep 2018 16:13:07 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Fri, 07 Sep 2018 16:13:07 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'mst@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 07, 2018 at 03:41:52PM +0800, Jason Wang wrote: > > > @@ -556,10 +667,14 @@ static void handle_tx_copy(struct vhost_net *net, struct socket *sock) > > > size_t len, total_len = 0; > > > int err; > > > int sent_pkts = 0; > > > + bool bulking = (sock->sk->sk_sndbuf == INT_MAX); > > What does bulking mean? > > The name is misleading, it means whether we can do batching. For simplicity, > I disable batching is sndbuf is not INT_MAX. But what does batching have to do with sndbuf? > > > for (;;) { > > > bool busyloop_intr = false; > > > + if (nvq->done_idx == VHOST_NET_BATCH) > > > + vhost_tx_batch(net, nvq, sock, &msg); > > > + > > > head = get_tx_bufs(net, nvq, &msg, &out, &in, &len, > > > &busyloop_intr); > > > /* On error, stop handling until the next kick. */ > > > @@ -577,14 +692,34 @@ static void handle_tx_copy(struct vhost_net *net, struct socket *sock) > > > break; > > > } > > > - vq->heads[nvq->done_idx].id = cpu_to_vhost32(vq, head); > > > - vq->heads[nvq->done_idx].len = 0; > > > - > > > total_len += len; > > > - if (tx_can_batch(vq, total_len)) > > > - msg.msg_flags |= MSG_MORE; > > > - else > > > - msg.msg_flags &= ~MSG_MORE; > > > + > > > + /* For simplicity, TX batching is only enabled if > > > + * sndbuf is unlimited. > > What if sndbuf changes while this processing is going on? > > We will get the correct sndbuf in the next run of handle_tx(). I think this > is safe. If it's safe why bother with special-casing INT_MAX? -- MST