benchmark of context switch? (latency)

[jayden5414]

trafficstars

这个参数对我们的业务比较重要. 谢谢啊!

[beef9999]

The context switch latency varies from 10 to 20 nano seconds depending how many coroutines you are running with.

We already have a test case for this. https://github.com/alibaba/PhotonLibOS/blob/0fa93f3e58d554f935ec62538d054f4d6595838f/thread/test/test.cpp#L380-L398

You can run it on your environment.

[beef9999]

But I wonder why context switch is what you are concerned. It doesn't weigh too much in the whole IO process, only a small portion, I believe.

Can you describe your scenario?

[jiangdongzi]

10 to 20 nano seconds

wonderful, can not believe, as I know the bthread which is a coroutine in brpc context switch time is 2~3 us..........

[ghost]

But I wonder why context switch is what you are concerned. It doesn't weigh too much in the whole IO process, only a small portion, I believe.

Can you describe your scenario?

high frenquency trading. it is latency sensitive.

[jiangdongzi]

The context switch latency varies from 10 to 20 nano seconds depending how many coroutines you are running with.

We already have a test case for this.

https://github.com/alibaba/PhotonLibOS/blob/0fa93f3e58d554f935ec62538d054f4d6595838f/thread/test/test.cpp#L380-L398

You can run it on your environment.

In my computer, AMD Ryzen 7 3700X 8-Core Processor, 3.6G hz, single context switch is 182.6550 ns.

[beef9999]

test_thread_switch:single context switch: 12.5599 ns (79.6185 M/s)

2.6 GHz Intel Core i7, macOS

[lihuiba]

@jiangdongzi Did you forget to add -O2? 182ns is too high