Java Wall Clock Time Vs Cpu Time

Wall clock time cpu time unless you have multiple cpus.

Java wall clock time vs cpu time.

The first is cpu time. Ocp 11 book oca 8 book ocp 8 book practice tests book blog javaranch faq how to ask questions book promos other certs. The option is called use thread cpu timer solaris only. The wall clock time is 9 seconds.

Real time is the total elapsed time of the gc event. It s easier to express the possible relationship as a ratio of cpu time wall clock time which is to say cpu second. Wallclock time is the total time between starting an operation and it completing. Cpu time is not wall time as in a clock on the wall.

It used to be chargeable that s why it was tracked separately. In the example above cpu time was lower than wall clock time but other relationships are possible. A cpu time approach is available but currently only on solaris. The cpu must service many processes every second not just yours so your process only gets small task slices in between processing other requests.

The cpu time spent is 8 seconds 5 seconds for cpu 1 and 2 seconds followed by 1 second for cpu 2. The netbeans default is to use wall clock absolute time for all method timing calculations. If this is a single threaded process. This is the time that your code actually spends executing code on the cpu.

The process spent all of its time using the cpu. The other type of time that we re interested in measuring is wallclock time. Cpu time is the total execution time or runtime for which the cpu was dedicated to a process. Wall time is thus different from cpu time which measures only the time during which the processor is actively working on a certain task.

If cpu time is desired it can be enabled from the advanced settings area in the attach profiler window. This means executing cpu time spent in system calls within the kernel as opposed to library. Each of those small task slices is counted toward the total execution time. A faster cpu will likely make the program run faster.

This is basically the time that you see in the clock. Sys time is the amount of cpu time spent in the kernel. User time is the cpu time spent in user mode code outside the kernel. Wall clock time is elapsed time the time on the clock on the wall.

In other words it is the difference between the time at which a task finishes and the time at which the task started.