Question

In my question profiling: deque is 23% of my runtime i have a problem with ‘new’ being a large % of my runtime. The problems are

I have to use the new keyword a lot and on many different classes/structs (i have >200 of them and its by design). I use lots of stl objects, iterators and strings. I use strdup and other allocation (or free) functions.

I have one function that is called >2million times. All it did was create stl iterators and it took up >20% of the time (however from what i remember stl is optimized pretty nicely and debug makes it magnitudes slower).

But keeping in mind i need to allocate and free these iterators >2m times along with other functions that are called often. How do i optimize the new and malloc keyword/function? Especially for all these classes/structs and classes/struct i didnt write (stl and others)

Although profiling says i (and stl?) use the new keyword more then anything else.

Answer 1

Look for opportunities to avoid the allocation/freeing, either by adding your own management layer to recycle memory and objects that have already been allocated, or modifying their allocators. There are plenty of articles on STL Allocators:

• http://www.codeguru.com/cpp/cpp/cpp_mfc/stl/article.php/c4079
• http://bmagic.sourceforge.net/memalloc.html
• http://www.codeproject.com/KB/stl/blockallocator.aspx

I have seen large multimap code go from unusably slow to very fast simply by replacing the default allocator.