![]() The structure definition shown at the start of this page was taken from 4.3BSD Reno.Īncient systems provided a vtimes() function with a similar purpose to getrusage(). Nonconformance is rectified in Linux 2.6.9 and later. Returned by RUSAGE_CHILDREN, although POSIX.1-2001 explicitly prohibits this. Then the resource usages of child processes are automatically included in the value In Linux kernel versions before 2.6.9, if the disposition of SIGCHLD is set to SIG_IGN Including is not required these days, but increases portability. Resource usage metrics are preserved across an execve(2). POSIX.1 specifies getrusage(), but specifies │ getrusage() │ Thread safety │ MT-Safe │ On error, -1 is returned, and errno is set appropriately.ĮRRORS EFAULT usage points outside the accessible address space.įor an explanation of the terms used in this section, see attributes(7). The number of times a context switch resulted due to a higher priority processīecoming runnable or because the current process exceeded its time slice. Up the processor before its time slice was completed (usually to await availability ![]() The number of times a context switch resulted due to a process voluntarily giving The number of times the filesystem had to perform output. The number of times the filesystem had to perform input. The number of page faults serviced that required I/O activity. The number of page faults serviced without any I/O activity here I/O activity isĪvoided by “reclaiming” a page frame from the list of pages awaiting reallocation. This is the resident set size of the largest child, not the maximum resident set ![]() This is the maximum resident set size used (in kilobytes). This is the total amount of time spent executing in kernel mode, expressed in a Timeval structure (seconds plus microseconds). This is the total amount of time spent executing in user mode, expressed in a May one day be supported on Linux.) The fields are interpreted as follows: Unmaintained fields are provided for compatibility with other systems, and because they Not all fields are completed unmaintained fields are set to zero by the kernel. Long ru_nivcsw /* involuntary context switches */ Long ru_nvcsw /* voluntary context switches */ Long ru_msgrcv /* IPC messages received */ Long ru_oublock /* block output operations */ Long ru_inblock /* block input operations */ Long ru_majflt /* page faults (hard page faults) */ ![]() Long ru_minflt /* page reclaims (soft page faults) */ Long ru_isrss /* integral unshared stack size */ Long ru_idrss /* integral unshared data size */ Long ru_ixrss /* integral shared memory size */ Long ru_maxrss /* maximum resident set size */ Struct timeval ru_stime /* system CPU time used */ Struct timeval ru_utime /* user CPU time used */ The resource usages are returned in the structure pointed to by usage, which has the Test macro must be defined (before including any header file) in order to obtain ![]() Return resource usage statistics for the calling thread. These statistics will include the resources usedīy grandchildren, and further removed descendants, if all of the interveningĭescendants waited on their terminated children. Return resource usage statistics for all children of the calling process that have Resources used by all threads in the process. Return resource usage statistics for the calling process, which is the sum of P.S I'm dividing these fields by No of Clock ticks in a second in order to calculate system CPU time and User CPU time in seconds as utime and stime are expressed in terms of CPU clock ticks.SYNOPSIS #include #include int getrusage(int who, struct rusage * usage ) DESCRIPTION getrusage() returns resource usage measures for who, which can be one of the following: NOTE: Please let me know if I'm evaluating wrong fields for system and user CPU time for a process? Or what is the right way to calculate? I validated output of atop command for system and user CPU time but my calculation is coming out wrong. For CPU time consumption in user mode I'm using the formula: (utime/ No of clock ticks) I'm calculating CPU time consumption(in seconds) in system mode using following formula: (stime / No of clock ticks). stime: Amount of time that this process has been scheduled in kernel(system) mode.utime: Amount of time that this process has been scheduled in user mode.There are two fields utime and stime in /proc//stat file, whose documentation says: I want to calculate CPU time consumption of a particular process in system mode and user mode using statistics present in /proc/. ![]()
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