NAME

getrusage − get information about resource utilization

SYNOPSIS

#include <sys/time.h>
#include <sys/resource.h>
#defineRUSAGE_SELF 0 /∗ calling process ∗/
#defineRUSAGE_CHILDREN -1 /∗ terminated child processes ∗/
getrusage(who, rusage)
int who;
struct rusage ∗rusage;

DESCRIPTION

getrusage returns information describing the resources utilized by the current process, or all its terminated child processes.  The who parameter is one of RUSAGE_SELF or RUSAGE_CHILDREN.  The buffer to which rusage points is filled in with the following structure:

structrusage {
struct timeval ru_utime;/∗ user time used ∗/
struct timeval ru_stime;/∗ system time used ∗/
intru_maxrss;
intru_ixrss;/∗ integral shared text memory size ∗/
intru_idrss;/∗ integral unshared data size ∗/
intru_isrss;/∗ integral unshared stack size ∗/
intru_minflt;/∗ page reclaims ∗/
intru_majflt;/∗ page faults ∗/
intru_nswap;/∗ swaps ∗/
intru_inblock;/∗ block input operations ∗/
intru_oublock;/∗ block output operations ∗/
intru_msgsnd;/∗ messages sent ∗/
intru_msgrcv;/∗ messages received ∗/
intru_nsignals;/∗ signals received ∗/
intru_nvcsw;/∗ voluntary context switches ∗/
intru_nivcsw;/∗ involuntary context switches ∗/
};

The fields are interpreted as follows:

ru_utime the total amount of time spent executing in user mode. 

ru_stime the total amount of time spent in the system executing on behalf of the process(es). 

ru_maxrss the maximum resident set size utilized (in kilobytes). 

ru_ixrss an “integral” value indicating the amount of memory used by the text segment that was also shared among other processes.  This value is expressed in units of kilobytes ∗ seconds-of-execution and is calculated by summing the number of shared memory pages in use each time the internal system clock ticks and then averaging over 1 second intervals. 

ru_idrss an integral value of the amount of unshared memory residing in the data segment of a process (expressed in units of kilobytes ∗ seconds-of-execution). 

ru_isrss an integral value of the amount of unshared memory residing in the stack segment of a process (expressed in units of kilobytes ∗ seconds-of-execution). 

ru_minflt the number of page faults serviced without any I/O activity; here I/O activity is avoided by “reclaiming” a page frame from the list of pages awaiting reallocation. 

ru_majflt the number of page faults serviced that required I/O activity. 

ru_nswap the number of times a process was “swapped” out of main memory. 

ru_inblock the number of times the file system had to perform input. 

ru_outblock the number of times the file system had to perform output. 

ru_msgsnd the number of IPC messages sent. 

ru_msgrcv the number of IPC messages received. 

ru_nsignals the number of signals delivered. 

ru_nvcsw the number of times a context switch resulted due to a process voluntarily giving up the processor before its time slice was completed (usually to await availability of a resource). 

ru_nivcsw the number of times a context switch resulted due to a higher priority process becoming runnable or because the current process exceeded its time slice. 

NOTES

The numbers ru_inblock and ru_outblock account only for real I/O; data supplied by the caching mechanism is charged only to the first process to read or write the data. 

ERRORS

The possible errors for getrusage are:

[EINVAL] The who parameter is not a valid value. 

[EFAULT] The address specified by the rusage parameter is not in a valid part of the process address space. 

SEE ALSO

gettimeofday(2), wait(2)

BUGS

There is no way to obtain information about a child process that has not yet terminated. 

September 02, 1992