SSL write/read performance

valmiki valmikibow at
Wed Apr 10 09:32:01 UTC 2019

Hi All,

I'm trying to understand server and client code over tcp using openssl.

How does the flow work when we do SSL_write or SSL_read.

SSL_write -> send buffer to kernel crypto subsystem -> take encrypted buffer and send it over network socket.

Is the above understanding correct ?

If its correct we have following context switch from user to kernel space and vice versa

-> open ssl libary to kernel crypto subsystem

-> kernel crypto subsystem to ssl library

-> ssl library to network subsystem

Does this mean for sending a buffer we need to three context switches from user to kernel and vice versa ?

Doesn't this effect performance ?

Please correct me if my understanding is wrong.


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