UDP Loopback Timing

Question

I initialized Wiznet w5100 and then I created UDP socket of 2kb buffer size. I connected Linux System with W5100. The loop back time I saw in Linux system is 3.5 milli seconds, which is more than the excepted time. The MCU that connected with wiznet is operating at 48 MHz with 12 MHz SPI Speed. The following is the time excepted to loop back data of size 1 byte: Total read using interrupt: 57 micro seconds Total write : 42 micro seconds Total time : 99 micro seconds I have also integrated the Wiznet API driver, but the loop back time is still around 3.7 milli seconds. Please help me resolve this ASAP. Thanks in advance, Conan.

Eugeny · Answer

Resolve what? You want some application of your linux host to show 99 microseconds? Your post misses a lot of information, and it is not clear how did you get 99 us. And your post sounds like statement of work rather than problem desciprion (“I want byte to return in 99 us”), and performance tuning requires deep knowledge about networking and platforms/software you use.

Conan · Answer

Hi Eugeny, Thanks for the quick response! The Linux system is having a UDP Client code. I calculated the time before sending and after receiving the data. For Linux to Linux it shows a total time of 0.5 milliseconds, but using the Wiznet W5100 IC, it takes around 3 milliseconds (instead of the expected 99microseconds). This 99 microseconds is the total expected time for writing and reading SPI registers based on calculations. The Wiznet IC is connected directly to the system (No Ethernet Hub is used). I want to know the response time of the Wiznet w5100 after receiving data from client using RECV interrupt and send response time after send command (The communication response time of the IC), as I cant find any availiable information regarding this; and also how I can optimize it, if optimization is possible.

Conan · Answer

@wizteam Can you provide any information/suggestions on the matter as well?