Java Wall Clock Time Vs Cpu Time

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Java wall clock time vs cpu time.

Cpu time is not wall time as in a clock on the wall. If this is a single threaded process. In other words it is the difference between the time at which a task finishes and the time at which the task started. Elapsed real time real time wall clock time or wall time is the actual time taken from the start of a computer program to the end.

Real time is the total elapsed time of the gc event. A cpu time approach is available but currently only on solaris. The first is cpu time. Wallclock time is the total time between starting an operation and it completing.

The netbeans default is to use wall clock absolute time for all method timing calculations. This is basically the time that you see in the clock. It used to be chargeable that s why it was tracked separately. Wall clock time is elapsed time the time on the clock on the wall.

Wall time is thus different from cpu time which measures only the time during which the processor is actively working on a certain task. It s easier to express the possible relationship as a ratio of cpu time wall clock time which is to say cpu second. Each of those small task slices is counted toward the total execution time. Ocp 11 book oca 8 book ocp 8 book practice tests book blog javaranch faq how to ask questions book promos other certs.

In the example above cpu time was lower than wall clock time but other relationships are possible. Sys time is the amount of cpu time spent in the kernel. The cpu time spent is 8 seconds 5 seconds for cpu 1 and 2 seconds followed by 1 second for cpu 2. This is the time that your code actually spends executing code on the cpu.

User time is the cpu time spent in user mode code outside the kernel. The wall clock time is 9 seconds. Wall clock time cpu time unless you have multiple cpus. If cpu time is desired it can be enabled from the advanced settings area in the attach profiler window.

Cpu time is the total execution time or runtime for which the cpu was dedicated to a process. The other type of time that we re interested in measuring is wallclock time. The process spent all of its time using the cpu. This means executing cpu time spent in system calls within the kernel as opposed to library.

A faster cpu will likely make the program run faster.