On 18/03/16 00:45, Lu, Wenzhuo wrote: > Hi Zoltan, > > >> -----Original Message----- >> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Zoltan Kiss >> Sent: Friday, March 18, 2016 1:11 AM >> To: Wu, Jingjing; dev at dpdk.org >> Subject: Re: [dpdk-dev] ixgbe TX function selection >> >> >> >> On 10/03/16 07:51, Wu, Jingjing wrote: >>> Hi, Zoltan >>> >>>> -----Original Message----- >>>> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Zoltan Kiss >>>> Sent: Wednesday, March 2, 2016 3:19 AM >>>> To: dev at dpdk.org >>>> Subject: [dpdk-dev] ixgbe TX function selection >>>> >>>> Hi, >>>> >>>> I've noticed that ixgbe_set_tx_function() selects the non-SG function >>>> even if (dev->data->scattered_rx == 1). That seems a bit dangerous, >>>> as you can turn that on inadvertently when you don't set >>>> max_rx_pkt_len and buffer size in certain ways. I've learnt it in the >>>> hard way, as my segmented packets were leaking memory on the TX path, >>>> which doesn't cries if you send out segmented packets. >>>> How should this case be treated? Assert on the non-SG TX side for the >>>> 'next' pointer? Or turning on SG if RX has it? It doesn't seem to be >>>> a solid way as other interfaces still can have SG turned on. >>>> >>> >>> If you look into the ixgbe_set_tx_function, you will find tx function >>> selection is decided by the tx_flags on queue configure, which is >>> passed by rte_eth_txconf. So even you set dev->data->scattered_rx to >>> 1, if the tx_flags is ETH_TXQ_FLAGS_NOMULTSEGS, ixgbe_xmit_pkts_simple >>> is still selected as tx function. So, you'd better to set tx_flags=0, and >>> have a try. >> >> You mean getting default_txconf from rte_eth_dev_info_get() and explicitly >> turn >> ETH_TXQ_FLAGS_NOMULTSEGS to 0? (filling tx_flags with zeros doesn't work >> very well) That's a way to solve it for me, but I'm rather talking about >> using >> defaults which doesn't cause memory leak quite easily. > Yes, ETH_TXQ_FLAGS_NOMULTSEGS only can be set to 1 when you know all your > packets will not be segmented. > I think that means normally we should use full function path for TX, for we > have no knowledge about if the packets will be segmented or not. > You don't need to set tx_flags to 0, only the ETH_TXQ_FLAGS_NOMULTSEGS bit > should be 0, the other bits can be 1 if needed.
So can we agree that the default settings should set ETH_TXQ_FLAGS_NOMULTSEGS to 0? > >> >>> >>>> Regards, >>>> >>>> Zoltan