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64-bit and 32-bit applications, C, C++, .NET, and dlls generated by any language compiler. Performance and memory profiler that identifies time-intensive functions and detects memory leaks and errors. Proprietary gprof: Linux/Unix Any language supported by gcc: Several tools with combined sampling and call-graph profiling.
Profilers interrupt program execution to collect information, which may result in a limited resolution in the time measurements, which should be taken with a grain of salt. Basic block profilers report a number of machine clock cycles devoted to executing each line of code, or a timing based on adding these together; the timings reported per ...
In C++11, this technique is known as generalized constant expressions (constexpr). [2] C++14 relaxes the constraints on constexpr – allowing local declarations and use of conditionals and loops (the general restriction that all data required for the execution be available at compile-time remains).
The Time Stamp Counter was once a high-resolution, low-overhead way for a program to get CPU timing information. With the advent of multi-core/hyper-threaded CPUs, systems with multiple CPUs, and hibernating operating systems, the TSC cannot be relied upon to provide accurate results — unless great care is taken to correct the possible flaws: rate of tick and whether all cores (processors ...
stat: measure total event count for single program or for system for some time; top: top-like dynamic view of hottest functions; record: measure and save sampling data for single program [13] report: analyze file generated by perf record; can generate flat, or graph profile. [13] annotate: annotate sources or assembly
When a program wants to time its own operation, it can use a function like the POSIX clock() function, which returns the CPU time used by the program. POSIX allows this clock to start at an arbitrary value, so to measure elapsed time, a program calls clock(), does some work, then calls clock() again. [1] The difference is the time needed to do ...
The reported time is a time used by both seq and wc -l added up. Format of the output can be adjusted using TIMEFORMAT variable. The time is not a builtin, but a special keyword, and can't be treated as a function or command. It also ignores pipeline redirections (even when executed as time -p, unless entire Bash is run in "POSIX mode").
An experiment done in 1996 indicates that approximately 6–13% of execution time is spent simply dispatching to the correct function, though the overhead can be as high as 50%. [5] The cost of virtual functions may not be so high on modern CPU architectures due to much larger caches and better branch prediction.