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On Jan 30, 2019, at 5:36 PM, Harsh Patel
<[email protected]<mailto:[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]<mailto:[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]<mailto:[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]<mailto:[email protected]>> wrote:
> On Jan 3, 2019, at 12:12 PM, Harsh Patel
> <[email protected]<mailto:[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<http://libns3.28.1-fd-net-device-debug.so>
> 5.080s
> rte_eth_rx_burst
> libns3.28.1-fd-net-device-debug.so<http://libns3.28.1-fd-net-device-debug.so>
> 3.558s
> ns3::DpdkNetDeviceReader::DoRead
> libns3.28.1-fd-net-device-debug.so<http://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]<mailto:[email protected]>> wrote:
>
>
> > On Dec 29, 2018, at 4:03 PM, Harsh Patel
> > <[email protected]<mailto:[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<http://libns3.28.1-fd-net-device-debug.so>
> > 3.522s
> > ns3::DpdkNetDeviceReader::DoRead
> > libns3.28.1-fd-net-device-debug.so<http://libns3.28.1-fd-net-device-debug.so>
> > 2.470s
> > rte_eth_rx_burst
> > libns3.28.1-fd-net-device-debug.so<http://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>
