Testing performance of C++ code

Question

What free tools could I use to test the performance of C++ code in Linux? Basically I want to identify the bottleneck of the code and improve on the performance. My application mainly involves computational code using the data from the network. So I would like to improve the speed of execution of the code.

Thanks.

Answer 1

For typical performance benchmarking this is what i use.

• gprof/oprofile - for CPU intensive profiling of your code.
• netstat/ethereal - for network statistics
• iostat/sar - for I/O
• vmstat - for memory
• mpstat/sar - for cpu usage

Now u can isolate the problems based on the output of these tools.

For eg:- if I/O is constant and within limits u can eliminate I/O as a problem. If CPU usage is heavy as shown my mpstat then get into profiling using gprof/oprofile.

Without the use of all of them together for different runs, its difficult to identify the bottleneck.

Note: U can write a script to run all of them together and store the results in designated folders for each run.

Answer 2

By far the best profiler for Linux that I know of is Zoom. Although it's a commercial product it's not too expensive and you can get a free 30 day evaluation licence on request

Answer 3

I recommend valgrind for

• cpu usage, callgrind submodule (source line granularity)
• memory leaks
• building call graphs
• some advanced issues like finding problems in multithread locking mechanism

The callgrind output can be visually displayed via KCacheGrind.

Answer 4

As @Paul says, give Zoom a try.

Personally, I use this method, which works for these reasons, and Zoom approximates it. It is a technique that some programmers have independently discovered.

I'm also told OProfile can do it, but you have to know what you need to make it do.