Messages in this thread | | | Date | Wed, 28 Nov 2012 14:48:52 +0800 | From | Jason Wang <> | Subject | Re: [net-next RFC] pktgen: don't wait for the device who doesn't free skb immediately after sent |
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On 11/28/2012 12:49 AM, Stephen Hemminger wrote: > On Tue, 27 Nov 2012 14:45:13 +0800 > Jason Wang <jasowang@redhat.com> wrote: > >> On 11/27/2012 01:37 AM, Stephen Hemminger wrote: >>> On Mon, 26 Nov 2012 15:56:52 +0800 >>> Jason Wang <jasowang@redhat.com> 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 <jasowang@redhat.com> >>> 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. > --
Not sure this is the best method, since pktgen was used to test the tx process of the device driver and NIC. If we use skb_orhpan(), we would miss the test of tx completion part.
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