From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [net-next RFC] pktgen: don't wait for the device who doesn't free skb immediately after sent Date: Tue, 27 Nov 2012 08:49:19 -0800 Message-ID: <20121127084919.1587c647@nehalam.linuxnetplumber.net> References: <1353916612-6357-1-git-send-email-jasowang@redhat.com> <20121126093728.0a10f97f@nehalam.linuxnetplumber.net> <50B46179.4040809@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: mst@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, davem@davemloft.net To: Jason Wang Return-path: In-Reply-To: <50B46179.4040809@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org List-Id: netdev.vger.kernel.org On Tue, 27 Nov 2012 14:45:13 +0800 Jason Wang wrote: > On 11/27/2012 01:37 AM, Stephen Hemminger wrote: > > On Mon, 26 Nov 2012 15:56:52 +0800 > > Jason Wang wrote: > > > >> Some deivces do not free the old tx skbs immediately after it has been sent > >> (usually in tx interrupt). One such example is virtio-net which optimizes for > >> virt and only free the possible old tx skbs during the next packet sending. This > >> would lead the pktgen to wait forever in the refcount of the skb if no other > >> pakcet will be sent afterwards. > >> > >> Solving this issue by introducing a new flag IFF_TX_SKB_FREE_DELAY which could > >> notify the pktgen that the device does not free skb immediately after it has > >> been sent and let it not to wait for the refcount to be one. > >> > >> Signed-off-by: Jason Wang > > Another alternative would be using skb_orphan() and skb->destructor. > > There are other cases where skb's are not freed right away. > > -- > > To unsubscribe from this list: send the line "unsubscribe netdev" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > Hi Stephen: > > Do you mean registering a skb->destructor for pktgen then set and check > bits in skb->tx_flag? Yes. Register a destructor that does something like update a counter (number of packets pending), then just spin while number of packets pending is over threshold.