'User' and 'Sys' come from wait (2) ( POSIX) or times (2) ( POSIX), depending on the particular system. The statistics reported by time are gathered from various system calls. Origins of the statistics reported by time (1) by wait(2) or waitpid(2), although the underlying system calls return the statistics for the process and its children separately. Note that in the output these figures include the User and Sys time of all child processes (and their descendants) as well when they could have been collected, e.g. Note that this is across all CPUs, so if the process has multiple threads (and this process is running on a computer with more than one processor) it could potentially exceed the wall clock time reported by Real (which usually occurs). User+Sys will tell you how much actual CPU time your process used. See below for a brief description of kernel mode (also known as 'supervisor' mode) and the system call mechanism. Like 'user', this is only CPU time used by the process. This means executing CPU time spent in system calls within the kernel, as opposed to library code, which is still running in user-space. Sys is the amount of CPU time spent in the kernel within the process. Other processes and time the process spends blocked do not count towards this figure. This is only actual CPU time used in executing the process. User is the amount of CPU time spent in user-mode code (outside the kernel) within the process. 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). Real is wall clock time - time from start to finish of the call. Real refers to actual elapsed time User and Sys refer to CPU time used only by the process. One of these things is not like the other. Real, User and Sys process time statistics
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |