> -----Original Message----- > From: Eric Dumazet [mailto:eric.dumazet@xxxxxxxxx] > Sent: Wednesday, May 6, 2015 11:09 AM > To: KY Srinivasan > Cc: davem@xxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxxxx; olaf@xxxxxxxxx; > apw@xxxxxxxxxxxxx; jasowang@xxxxxxxxxx > Subject: Re: [PATCH V3 net-next 1/1] hv_netvsc: Use the xmit_more skb flag > to optimize signaling the host > > On Wed, 2015-05-06 at 11:20 -0700, K. Y. Srinivasan wrote: > > Based on the information given to this driver (via the xmit_more skb flag), > > we can defer signaling the host if more packets are on the way. This will > help > > make the host more efficient since it can potentially process a larger batch > of > > packets. Implement this optimization. > > > > diff --git a/drivers/net/hyperv/netvsc_drv.c > b/drivers/net/hyperv/netvsc_drv.c > > index 5993c7e..4efaa6e 100644 > > --- a/drivers/net/hyperv/netvsc_drv.c > > +++ b/drivers/net/hyperv/netvsc_drv.c > > @@ -435,6 +435,8 @@ check_size: > > packet->page_buf = page_buf; > > > > packet->q_idx = skb_get_queue_mapping(skb); > > + if (netif_tx_queue_stopped(netdev_get_tx_queue(net, packet- > >q_idx))) > > + packet->xmit_more = false; > > Have you tested this condition ever triggers ? > > It should not. > > netvsc_start_xmit() should not be called if the queue is stopped. > > The problem is the following : > > netvsc_start_xmit() is called with the packet that is going to stop the > queue, filling last slot, but with skb->xmit_more = 1; > > So you need to do something about xmit_more, after calling > netif_tx_stop_queue(), not before. Ah! I too was wondering how we could get into this situation. The condition you mention is already handled in the lower level - if the attempt to put the last packet on vmbus were to fail because the ring is full, we will notify the host independent of kick_q parameter - look at the function vmbus_sendpacket_ctl() in drivers/hv/channel.c I will resend the patch by reverting this to version 2. Regards, K. Y > > _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
