SoylentNews is people
SoylentNews
posted by
LaminatorX
on Sunday March 16 2014, @03:28AM
from the premature-optimization-is-the-root-of-all-evil dept.
from the premature-optimization-is-the-root-of-all-evil dept.
Subsentient writes:
"I've been writing C for quite some time, but I never followed good conventions I'm afraid, and I never payed much attention to the optimization tricks of the higher C programmers. Sure, I use const when I can, I use the pointer methods for manual string copying, I even use register for all the good that does with modern compilers, but now, I'm trying to write a C-string handling library for personal use, but I need speed, and I really don't want to use inline ASM. So, I am wondering, what would other Soylenters do to write efficient, pure, standards-compliant C?"
This discussion has been archived.
No new comments can be posted.
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
Can anyone remember when the times were not hard, and money not scarce?
(Score: 4, Insightful) by maxwell demon on Sunday March 16 2014, @08:45PM
However today neither counting instruction, nor adding cycles is going to give a good estimate about your running time (unless it turns out e.g. that the loop is slightly too large to fit into the instruction cache), because the processors tend to do a lot behind the scenes (register renaming, branch prediction, out-of-order execution, speculative execution, ...). Far more important issues are things like cache locality (this alone can get you quite a bit of speedup, and can be analyzed entirely on the C level). And of course no amount of micro-optimization can save you from a badly chosen algorithm.
The Tao of math: The numbers you can count are not the real numbers.