Effect of Implementation Choices

Posted Aug 4, 2005 16:21 UTC (Thu) by eru (subscriber, #2753)
In reply to: Our bloat problem by elanthis
Parent article: Our bloat problem

That isn't generally how a terminal scrollback buffer works, however. You generally work with blocks of memory, so even blank areas on lines are filled in with data.

But that is a very wasteful implementation choice. There are several other ways of doing it (like the linked list I proposed) that are not much more complex to program. I forgot about attributes in my original post, but they, too can easily be represented in ways that average much less than 4 bytes per character. And as another poster pointed out, you can store Unicode with less than 4 bytes per character. In today's computers the CPU is so much faster than the memory that it may not pay to optimize data structures for fast access at the cost of increased size.

I think this difference illustrates a major reason for the bloat problem: using naive data structures and code without sufficient thought for efficiency. Maybe OK for prototypes, but not after that. I am not advocating cramming data into few bits in complex ways (as used to be common in the days of 8-bit microcomputers), but simply avoid wasting storage whenever it can be easily done. Like, don't store boolean flags or known-to-be small numbers in full-size ints, allocate space for just the useful data (like in the scroll-back case), don't replicate data redundantly.

I wonder if the well-known GNU coding guidelines (see Info node "standards" in Emacs installations) may be partly to blame for bloat problems in free software... To quote:

Memory Usage
============
If a program typically uses just a few meg of memory, don't bother making any effort to reduce memory usage. For example, if it is impractical for other reasons to operate on files more than a few meg long, it is reasonable to read entire input files into core to operate on them.

Right, but what when you have lots of programs open at the same time, each using "just a few meg of memory"? (I recognize Stallman wrote that before GUI's became common on *nix systems).