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What is the difference between real User and sys time?
Real, User and Sys process time statistics Real refers to actual elapsed time; User and Sys refer to CPU time used only by the process. User is the amount of CPU time spent in user-mode code (outside the kernel) within the process. This is only actual CPU time used in executing the process.
What is system time and User time?
User time is the amount of time the CPU was busy executing code in user space. System time is the amount of time the CPU was busy executing code in kernel space.
What is the meaning of real User and sys?
In brief, Real refers to actual elapsed time including other processes that may be running at the same time; User and Sys refer to CPU time used only by the process (here the df command). Sys is the amount of CPU time spent in the kernel within the process.
What does User time mean?
User Time. This is the amount of time the command spends in “User Mode.” User Mode is a “safety” feature because when a program is in User Mode it cannot cause other programs to crash, or behave unexpectedly. System Time.
Why is real time higher than user time?
As expected the elapsed real time is much larger than the others on this single user/single core process. real < user: The process is CPU bound and takes advantage of parallel execution on multiple cores/CPUs.
What do real, user, and sys mean?
Real refers to actual elapsed time; User and Sys refer to CPU time used only by the process. Real is wall clock time – time from start to finish of the call. This is all elapsed time including time slices used by other processes and time the process spends blocked (for example if it is waiting for I/O to complete).
What’s the difference between Sys and user time?
‘user’ time is the CPU time spent in user-mode code (outside the kernel). ‘Sys’ time is the amount of CPU time spent in the kernel. This means executing CPU time spent in system calls within the kernel, as opposed to library code, which is still running in user-space.
Why is the sys time bigger than the wall time?
The sys time is about the same for both as for a single process, but the wall time is larger because the processes are competing for disk read access likely. So it seems that it does in fact account for which process started a given kernel work.