> On Feb 5, 2019, at 12:37 AM, Harsh Patel <[email protected]> wrote: > > Hi, > > We would like to inform you that our code is working as expected and we are > able to obtain 95-98 Mbps data rate for a 100Mbps application rate. We are > now working on the testing of the code. Thanks a lot, especially to Keith for > all the help you provided. > > We have 2 main queries :- > 1) We wanted to calculate Backlog at the NIC Tx Descriptors but were not able > to find anything in the documentation. Can you help us in how to calculate > the backlog? > 2) We searched on how to use Byte Queue Limit (BQL) on the NIC queue but > couldn't find anything like that in DPDK. Does DPDK support BQL? If so, can > you help us on how to use it for our project?
what was the last set of problems if I may ask? > > Thanks & Regards > Harsh & Hrishikesh > > On Thu, 31 Jan 2019 at 22:28, Wiles, Keith <[email protected]> wrote: > > > Sent from my iPhone > > On Jan 30, 2019, at 5:36 PM, Harsh Patel <[email protected]> wrote: > >> Hello, >> >> This mail is to inform you that the integration of DPDK is working with ns-3 >> on a basic level. The model is running. >> For UDP traffic we are getting throughput same or better than raw socket. >> (Around 100Mbps) >> But unfortunately for TCP, there are burst packet losses due to which the >> throughput is drastically affected after some point of time. The bandwidth >> of the link used was 100Mbps. >> We have obtained cwnd and ssthresh graphs which show that once the flow gets >> out from Slow Start mode, there are so many packet losses that the >> congestion window & the slow start threshold is not able to go above 4-5 >> packets. > > Can you determine where the packets are being dropped? >> We have attached the graphs with this mail. >> > > I do not see the graphs attached but that’s OK. >> We would like to know if there is any reason to this or how can we fix this. > > I think we have to find out where the packets are being dropped this is the > only reason for the case to your referring to. >> >> Thanks & Regards >> Harsh & Hrishikesh >> >> On Wed, 16 Jan 2019 at 19:25, Harsh Patel <[email protected]> wrote: >> Hi >> >> We were able to optimise the DPDK version. There were couple of things we >> needed to do. >> >> We were using tx timeout as 1s/2048, which we found out to be very less. >> Then we increased the timeout, but we were getting lot of retransmissions. >> >> So we removed the timeout and sent single packet as soon as we get it. This >> increased the throughput. >> >> Then we used DPDK feature to launch function on core, and gave a dedicated >> core for Rx. This increased the throughput further. >> >> The code is working really well for low bandwidth (<~50Mbps) and is >> outperforming raw socket version. >> But for high bandwidth, we are getting packet length mismatches for some >> reason. We are investigating it. >> >> We really thank you for the suggestions given by you and also for keeping >> the patience for last couple of months. >> >> Thank you >> >> Regards, >> Harsh & Hrishikesh >> >> On Fri, Jan 4, 2019, 11:27 Harsh Patel <[email protected]> wrote: >> Yes that would be helpful. >> It'd be ok for now to use the same dpdk version to overcome the build >> issues. >> We will look into updating the code for latest versions once we get past >> this problem. >> >> Thank you very much. >> >> Regards, >> Harsh & Hrishikesh >> >> On Fri, Jan 4, 2019, 04:13 Wiles, Keith <[email protected]> wrote: >> >> >> > On Jan 3, 2019, at 12:12 PM, Harsh Patel <[email protected]> wrote: >> > >> > Hi >> > >> > We applied your suggestion of removing the `IsLinkUp()` call. But the >> > performace is even worse. We could only get around 340kbits/s. >> > >> > The Top Hotspots are: >> > >> > Function Module CPU Time >> > eth_em_recv_pkts librte_pmd_e1000.so 15.106s >> > rte_delay_us_block librte_eal.so.6.1 7.372s >> > ns3::DpdkNetDevice::Read libns3.28.1-fd-net-device-debug.so 5.080s >> > rte_eth_rx_burst libns3.28.1-fd-net-device-debug.so 3.558s >> > ns3::DpdkNetDeviceReader::DoRead libns3.28.1-fd-net-device-debug.so >> > 3.364s >> > [Others] 4.760s >> >> Performance reduced by removing that link status check, that is weird. >> > >> > Upon checking the callers of `rte_delay_us_block`, we got to know that >> > most of the time (92%) spent in this function is during initialization. >> > This does not waste our processing time during communication. So, it's a >> > good start to our optimization. >> > >> > Callers CPU Time: Total CPU Time: Self >> > rte_delay_us_block 100.0% 7.372s >> > e1000_enable_ulp_lpt_lp 92.3% 6.804s >> > e1000_write_phy_reg_mdic 1.8% 0.136s >> > e1000_reset_hw_ich8lan 1.7% 0.128s >> > e1000_read_phy_reg_mdic 1.4% 0.104s >> > eth_em_link_update 1.4% 0.100s >> > e1000_get_cfg_done_generic 0.7% 0.052s >> > e1000_post_phy_reset_ich8lan.part.18 0.7% 0.048s >> >> I guess you are having vTune start your application and that is why you have >> init time items in your log. I normally start my application and then attach >> vtune to the application. One of the options in configuration of vtune for >> that project is to attach to the application. Maybe it would help hear. >> >> Looking at the data you provided it was ok. The problem is it would not load >> the source files as I did not have the same build or executable. I tried to >> build the code, but it failed to build and I did not go further. I guess I >> would need to see the full source tree and the executable you used to really >> look at the problem. I have limited time, but I can try if you like. >> > >> > >> > Effective CPU Utilization: 21.4% (0.856 out of 4) >> > >> > Here is the link to vtune profiling results. >> > https://drive.google.com/open?id=1M6g2iRZq2JGPoDVPwZCxWBo7qzUhvWi5 >> > >> > Thank you >> > >> > Regards >> > >> > On Sun, Dec 30, 2018, 06:00 Wiles, Keith <[email protected]> wrote: >> > >> > >> > > On Dec 29, 2018, at 4:03 PM, Harsh Patel <[email protected]> >> > > wrote: >> > > >> > > Hello, >> > > As suggested, we tried profiling the application using Intel VTune >> > > Amplifier. We aren't sure how to use these results, so we are attaching >> > > them to this email. >> > > >> > > The things we understood were 'Top Hotspots' and 'Effective CPU >> > > utilization'. Following are some of our understandings: >> > > >> > > Top Hotspots >> > > >> > > Function Module CPU Time >> > > rte_delay_us_block librte_eal.so.6.1 15.042s >> > > eth_em_recv_pkts librte_pmd_e1000.so 9.544s >> > > ns3::DpdkNetDevice::Read libns3.28.1-fd-net-device-debug.so >> > > 3.522s >> > > ns3::DpdkNetDeviceReader::DoRead >> > > libns3.28.1-fd-net-device-debug.so 2.470s >> > > rte_eth_rx_burst libns3.28.1-fd-net-device-debug.so 2.456s >> > > [Others] 6.656s >> > > >> > > We knew about other methods except `rte_delay_us_block`. So we >> > > investigated the callers of this method: >> > > >> > > Callers Effective Time Spin Time Overhead Time Effective Time >> > > Spin Time Overhead Time Wait Time: Total Wait Time: Self >> > > e1000_enable_ulp_lpt_lp 45.6% 0.0% 0.0% 6.860s 0usec 0usec >> > > e1000_write_phy_reg_mdic 32.7% 0.0% 0.0% 4.916s 0usec >> > > 0usec >> > > e1000_read_phy_reg_mdic 19.4% 0.0% 0.0% 2.922s 0usec 0usec >> > > e1000_reset_hw_ich8lan 1.0% 0.0% 0.0% 0.143s 0usec 0usec >> > > eth_em_link_update 0.7% 0.0% 0.0% 0.100s 0usec 0usec >> > > e1000_post_phy_reset_ich8lan.part.18 0.4% 0.0% 0.0% 0.064s >> > > 0usec 0usec >> > > e1000_get_cfg_done_generic 0.2% 0.0% 0.0% 0.037s 0usec >> > > 0usec >> > > >> > > We lack sufficient knowledge to investigate more than this. >> > > >> > > Effective CPU utilization >> > > >> > > Interestingly, the effective CPU utilization was 20.8% (0.832 out of 4 >> > > logical CPUs). We thought this is less. So we compared this with the >> > > raw-socket version of the code, which was even less, 8.0% (0.318 out of >> > > 4 logical CPUs), and even then it is performing way better. >> > > >> > > It would be helpful if you give us insights on how to use these results >> > > or point us to some resources to do so. >> > > >> > > Thank you >> > > >> > >> > BTW, I was able to build ns3 with DPDK 18.11 it required a couple changes >> > in the DPDK init code in ns3 plus one hack in rte_mbuf.h file. >> > >> > I did have a problem including rte_mbuf.h file into your code. It appears >> > the g++ compiler did not like referencing the struct rte_mbuf_sched inside >> > the rte_mbuf structure. The rte_mbuf_sched was inside the big union as a >> > hack I moved the struct outside of the rte_mbuf structure and replaced the >> > struct in the union with ’struct rte_mbuf_sched sched;', but I am guessing >> > you are missing some compiler options in your build system as DPDK builds >> > just fine without that hack. >> > >> > The next place was the rxmode and the txq_flags. The rxmode structure has >> > changed and I commented out the inits in ns3 and then commented out the >> > txq_flags init code as these are now the defaults. >> > >> > Regards, >> > Keith >> > >> >> Regards, >> Keith >> >> <Ssthresh.png> >> <Cwnd.png> Regards, Keith
