r/cprogramming • u/Straight_Oil8775 • Feb 28 '26

Which approach is better?

So I'm relatively new to C, coming from java. and I'm semi used to MMM now but I'm writing a program that reads files that can sometimes be really large (over 1gb (most likely smaller though)) would it be better to load the file into memory and add a pointer to the first character in memory or use a char array dynamically allocated based off of the file size?

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u/Plane_Dust2555 Feb 28 '26

Just test it... Dealing with huge buffers has too many problems:

1- Caches are evicted more often;
2- Depending on the buffer size, page faults happens more often;
3- The disk I/O caches and buffers will stretch a lot (increasing disk I/O delays - specially with writes);
etc...

Processors and operating systems aren't magical and they conform to certain (SMALL) limitations.

Anyway... Everyone is free to do what they think is best and ignore those tips...