Which is longer User time or SYS time?
This is basically the time that you see on the clock. ‘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.
What does real user sys mean?
actual elapsed time
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.
Why is User time more than real time?
When real Time Is Greater Than user + sys Times Lack of CPU is when the application doesn’t get enough CPU cycles to run because they are shared among too many processes. The solution might be to add more CPU cores or to reduce the number of the most CPU-consuming processes.
Why is real time less than user and sys time?
In normal (all most all) GC events, real time will be less than user + sys time. It’s because of multiple GC threads work concurrently to share the work load, thus real time will be less than user + sys time. Say user + sys time is 2 seconds.
What causes my elapsed time much longer than user time?
Based on the fact that your program took as much system time as user time it was a very IO intensive thing. Reading from disk a lot or writing to disk a lot. RAM is pretty fast, a few hundred nanoseconds usually. So if everything fits in RAM elapsed time is usually just a little bit longer than user time.
What do real, user and sys statistics mean?
Real, User and Sys process time statistics One of these things is not like the other. Real refers to actual elapsed time; User and Sys refer to CPU time used only by the process. Realis wall clock time – time from start to finish of the call.
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.