From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Durrant Subject: RE: [Xen-devel] [PATCH v2 net-next 4/7] xen-netback: immediately wake tx queue when guest rx queue has space Date: Tue, 4 Oct 2016 13:56:15 +0000 Message-ID: <136ea81c65e847719c787c37679f8da3@AMSPEX02CL03.citrite.net> References: <1475573358-32414-1-git-send-email-paul.durrant@citrix.com> <1475573358-32414-5-git-send-email-paul.durrant@citrix.com> <20161004124854.GD30836@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Cc: "netdev@vger.kernel.org" , "xen-devel@lists.xenproject.org" , Wei Liu , David Vrabel To: Konrad Rzeszutek Wilk Return-path: Received: from smtp.ctxuk.citrix.com ([185.25.65.24]:20157 "EHLO SMTP.EU.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752780AbcJDOIF (ORCPT ); Tue, 4 Oct 2016 10:08:05 -0400 In-Reply-To: <20161004124854.GD30836@localhost.localdomain> Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: > -----Original Message----- > From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@oracle.com] > Sent: 04 October 2016 13:49 > To: Paul Durrant > Cc: netdev@vger.kernel.org; xen-devel@lists.xenproject.org; Wei Liu > ; David Vrabel > Subject: Re: [Xen-devel] [PATCH v2 net-next 4/7] xen-netback: immediately > wake tx queue when guest rx queue has space > > On Tue, Oct 04, 2016 at 02:29:15AM -0700, Paul Durrant wrote: > > From: David Vrabel > > > > When an skb is removed from the guest rx queue, immediately wake the > > tx queue, instead of after processing them. > > Please, could the description explain why? > Is it not reasonably obvious that it improves parallelism between filling and draining the queue? I could add a comment if you think it needs spelling out. Paul > > > > Signed-off-by: David Vrabel [re-based] > > Signed-off-by: Paul Durrant > > --- > > Cc: Wei Liu > > --- > > drivers/net/xen-netback/rx.c | 24 ++++++++---------------- > > 1 file changed, 8 insertions(+), 16 deletions(-) > > > > diff --git a/drivers/net/xen-netback/rx.c > > b/drivers/net/xen-netback/rx.c index b0ce4c6..9548709 100644 > > --- a/drivers/net/xen-netback/rx.c > > +++ b/drivers/net/xen-netback/rx.c > > @@ -92,27 +92,21 @@ static struct sk_buff *xenvif_rx_dequeue(struct > xenvif_queue *queue) > > spin_lock_irq(&queue->rx_queue.lock); > > > > skb = __skb_dequeue(&queue->rx_queue); > > - if (skb) > > + if (skb) { > > queue->rx_queue_len -= skb->len; > > + if (queue->rx_queue_len < queue->rx_queue_max) { > > + struct netdev_queue *txq; > > + > > + txq = netdev_get_tx_queue(queue->vif->dev, > queue->id); > > + netif_tx_wake_queue(txq); > > + } > > + } > > > > spin_unlock_irq(&queue->rx_queue.lock); > > > > return skb; > > } > > > > -static void xenvif_rx_queue_maybe_wake(struct xenvif_queue *queue) - > { > > - spin_lock_irq(&queue->rx_queue.lock); > > - > > - if (queue->rx_queue_len < queue->rx_queue_max) { > > - struct net_device *dev = queue->vif->dev; > > - > > - netif_tx_wake_queue(netdev_get_tx_queue(dev, queue- > >id)); > > - } > > - > > - spin_unlock_irq(&queue->rx_queue.lock); > > -} > > - > > static void xenvif_rx_queue_purge(struct xenvif_queue *queue) { > > struct sk_buff *skb; > > @@ -585,8 +579,6 @@ int xenvif_kthread_guest_rx(void *data) > > */ > > xenvif_rx_queue_drop_expired(queue); > > > > - xenvif_rx_queue_maybe_wake(queue); > > - > > cond_resched(); > > } > > > > -- > > 2.1.4 > > > > > > _______________________________________________ > > Xen-devel mailing list > > Xen-devel@lists.xen.org > > https://lists.xen.org/xen-devel