Allocating largest buffer without using swap

Question

In C/C++ under Linux, I need to allocate a large (several gigabyte) block of memory, in order to store real-time data from a sensor connected to the ethernet port and streaming

Answer 1

Well, under linux you can use mlock()/mlockall() to keep an adress range in physical memory and prevent it from being swapped out. The process using mlock needs a couple of privileges to do so, "man mlock" has the details. I am not sure about the maximum mlock'able block (it might differ from what seems to be "free"), so probably a binary search could help (lock a range, if that fails reduce the size of the area etc..)

On the other hand, 110MB/s is not really a problem for a Solid-State-Drive. A 60GB SSD with 280MB/s write speed costs about $200 on the corner. Just copy the sensor data into a small write buffer and stream that to the SSD.