| .) At our workplace, we use preallocation for almost everything. When we do dynamic allocations, typically it is from free-lists from pools that we pre-allocate. Almost all of our allocation/freeing costs are cheap O(1). Pretty much everything is zero-copy. That is why I cringe a little when I hear that GC's are "faster than manual MM". Because manual MM done well can eliminate almost all of the costs of memory management. I also cringe a little when I see "malloc" deep inside C functions. I really like the basic convention in C that you should pass needed allocations in as arguments (and it is virtually always possible) allowing these allocations to be members of of members of other allocations, aggregating allocations so there are much fewer. .) Information regarding heap-allocs is relatively easy to obtain with "oprofile", look up the time spent in "malloc" and "free" and the related functions underneath them. .) C makes it very easy to use an array of the values you want, rather than an indirection. For Lists, I don't think that is a useful idea. For hash tables, given that many entries are empty, I think it is a better trade-off to have your hash array as an indirection, though the buckets could be explicitly put together. And so on. I often encountered dynamic allocation overheads are noticeable or even huge chunks of my runtime when I had to work with code that used them. Reducing the dynamic allocation really helps. We're not safe, we need to work towards it explicitly. |