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kohler / click

The Click modular router: fast modular packet processing and analysis
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Click program with DPDK cause high CPU utilization on other cores even if using taskset and lcore option #506

Closed ShaofengWu123 closed 1 year ago

ShaofengWu123 commented 1 year ago

I am currently running a toy click program shown below: FromDPDKDevice(0000:03:00.0) -> Print -> Discard; This program simply polls pakcets from a physical interafce p0, print and discard. The command I use for running this config is: taskset -c 0 ./click-dpdk --dpdk -l 0-1 n 1 --file-prefix=dpdk0 -- ./test_connect.click
During runtime, when there is no incoming traffic, The CPU utilization shown by top makes sense. As shown below, cpu0 is polling packets from interface p0. image

But when I generate traffic from another machine to the machine under test(they are connected using a 100G switch), I observe that as the packet rate grows, the utilization of cores other than core 0 or core 1 also grow. And the CPU utilization of core 0 drops.
The CPU utilization when packet rate is 5Gbps: image The CPU utilization when packet rate is 10Gbps: image

It confuses me because I thought that the above command should provide good isolation of core usage, and even if the packet rate grows, cores other than cpu0/1 should remain un-disturbed. I test dpdk-testpmd under same setting and it shows exactly the behavior that only core 0 has 100% utilization and other cores remain ~0% utilization or say idle.

My question is: do I miss anything in configuring a click modular router program so that core usage can be isolated? Or click program should behave like this with dpdk? Thanks!

ShaofengWu123 commented 1 year ago

I have managed to find the cause for this problem. This is because I use vscode to connect into the server, and when the application prints a lot of information, vscode-related process will consume a lot of CPU. I think this issue can be closed with this explanation.